PLACE IN RETURN BOX to remove thlo checkout from your record. TO AVOID FINES rotum on or boron duo duo. DATE DUE DATE DUE DATE DUE THEE, 4 {ti-’9' L! f? MSU Is An Affirmative ActioNEqual Opportunity Institution 4a.; anfl' EVALUATION OF DIFFERENT BEAN DENSITIES IN RELATION TO SEED YIELD, PROTEIN, AND MINERAL NUTRIENT COMPOSITION OF BEANS (Phaseoius vulgaris L.) AND MAIZE (Zea maxs L.) GROWN IN ASSOCIATION AND IN MONOCULTURE By M. Emii T. Mmbaga A DISSERTATION Submitted to Michigan State University in partial fulfileent of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Crop and $011 Sciences 1989 IT‘S“ \f) (unifidyl ABSTRACT EVALUATION OF DIFFERENT BEAN DENSITIES IN RELATION TO SEED YIELD, PROTEIN, AND MINERAL NUTRIENT COMPOSITION OF BEANS (Phaseolus vulgaris L.) AND MAIZE (Zea mays L.) GROWN IN ASSOCIATION AND IN MONOCULTURE By M. Emil T. Mmbaga The potential for increasing yields by determining optimum bean population in associated culture was investigated at three densities using two bean cultivars grown in association with maize at East Lansing, Michigan. Nine treatment combinations were tested for three years in a randomized block design with four replications on a fine loamy soil. Pods/m2, leaf area index, biomass, and seed yield increased with increasing bean plant density. Stem and leaf dry weight of bean in association reached their maximum accumula- tion during the mid-pod filling phase and declined as physiological maturity was reached. Root dry weight of both bean cultivars at different densities under intercropping was similar throughout the reproductive phases of plant development. Optimum biomass produc- tion during the vegetative phase appeared to be a prerequisite for obtaining increased levels of yield components. Seed yield of both cultivars grown in association with maize was 61 to 68 percent lower than their corresponding monocultural seed yields. The highest leaf area index obtained from bean in association with maize was 3.3, whereas the monocultural value was 4.3. The relative light interception of the two bean cultivars in association was 47 to 57 percent lower than their light intercep- tion level under monoculture. Bean seed yield was positively and significantly correlated with seeds/pod, pods/m2, biomass, and leaf area index. The concentrations of macro and micronutrients in bean and maize plants were within the nutrient sufficiency range for normal growth and development. Land equivalent ratio increased with increasing bean densities and ranged between 1.15 and 1.35. An association of maize (40,000 plants/ha) with beans (150,000 plants/ha) produced optimum combined total seed yield per hectare as compared to the other density combinations for both crops. To my wonderful parents, for their love, moral support, constant encouragement, and everlasting inspiration. To Tuael, my wife, for her patience, kindness, and care throughout this period of study. To my children, Enea and Roseline, who have always loved and wished me joy, happiness, and success in my career; Daniel, for his continuous love and for advising me not to give up--"Don't quit, Dad"; Abel, for his interest in my work; and Edward, for his sweet smile and endless love. iv ACKNOWLEDGEMENTS I wish to express my appreciation to my major professor, Dr. M. Wayne Adams, for his understanding, the joy his leadership brought to me, for his wonderful friendship, for being a source of happiness and knowledge, for believing in me, for the enthusiasm, kindness, moral support, experience, encouragement, patient guidance, and for his constructive criticism in the preparation of this manuscript. Gratitude is expressed to Drs. George L. Hosfield, Alfred W. Saettler, James D. Kelly, and Alan R. Putnam for serving as guidance committee members. Their sharing of ideas and suggestions was fundamental in the preparation of this manuscript. I am most deeply grateful to Drs. M. Wayne Adams, George L. Hosfield, Donald R. Christenson, Boyd G. Ellis, James D. Kelly, Phu V. Nguyen, and Darryl D. Warncke for providing their lab and field work facilities. Their generosity resulted in the successful com- pletion of my Ph.D. program. Special thanks are extended to Dr. Russell D. Freed and Bede M. Okigbo for reading my manuscript and for their constructive sug- gestions and to Dr. Steven Sprecher for plotting my graphs. Special acknowledgements are extended to Jerry L. Taylor for his help during my field research; Tanzanian and Kenyan students at Michigan State University for helping me with field work for three seasons, bean group for their support during my field and laboratory work. Sincere thanks to Crop and Soil Sciences tech- nicians and graduate students with whom I had the privilege to work together and for their constant assistance. I sincerely express my appreciation to my brothers, sisters, in-laws, relatives, and friends, particularly those at TARO Lyamungu for their continuous love, moral support, and encourage- ment throughout my study. I deeply appreciate the scholarships awarded to me. My special and sincere thanks go to the government of the United Republic of Tanzania, USAID through Farming Systems Research and Bean/Cowpea CRSP Projects, and to the Food and Agriculture Organization (FAQ) for their financial support. vi laboratory work. Sincere thanks to Crop and Soil Sciences tech- nicians and graduate students with whom I had the privilege to work together and for their constant assistance. I sincerely express my appreciation to my brothers, sisters, in-laws, relatives, and friends, particularly those at TARO Lyamungu for their continuous love, moral support, and encourage- ment throughout my study. I deeply appreciate the scholarships awarded to me. My special and sincere thanks go to the government of the United Republic of Tanzania, USAID through Farming Systems Research and Bean/Cowpea CRSP Projects, and to the Food and Agriculture Organization (FAQ) for their financial support. vi TABLE OF CONTENTS LIST OF TABLES ....................... LIST OF FIGURES ...................... CHAPTER 1. 2. INTRODUCTION .................... REVIEW OF THE LITERATURE .............. 2.1. 2.2. 2.3. 2.4. 2.5. 2.6. 2.7. Bean Seed Yield and Yield-Related Traits 2.1.1. Bean Seed Yield in Association 2.1.2. Harvest Index ............. 2.1.3. Dry Weight Distribution ........ 2.1.4. Leaf Area ............... Maize Yield and Yield Components ....... 2.2.1. Grain Yield .............. 2.2.2 Land Equivalent Ratio ......... Light Interception in the Two Crapping Systems .................... Water Use in the Cropping Systems ....... Management Factors Influencing Productivity and Efficiency in the Two Cropping Systems 2.5.1. Component Crop Density ........ 2.5.2. Plant Configuration and Spacing . . . . 2.5.3. Time of Sowing ............ Pest Interactions in the Two Cropping Systems . Influence of Soil Nutrients in the Two Cropping Systems .................... vii xiii 10 11 16 17 17 17 21 25 26 26 27 28 29 36 CHAPTER 2.8. Nitrogen Fixation and Transfer by Legume Crop Component ................... 2.9. Plant Nutrient Concentration ......... MATERIALS AND METHODS ................ 3.1. Dry Weight .................. 3.2. Total Non-Structural Carbohydrate (TNC) Analysis ................... 3.3. Mineral Nutrient Concentration ........ 3.4. Light Penetration and Leaf Area ........ RESULTS ....................... 4.1. Bean Performance in the Two Cropping Systems 4.2. Bean Carbohydrate Concentration ........ 4.3. Bean Mineral Nutrients ............ 4.3.1. Bean Seed Mineral Nutrient Concentration ............. 4.3.2. Bean Leaf Mineral Nutrient Concentration ............. 4.4. Maize Performance in the Two Cropping Systems . 4.5. Maize Mineral Nutrient Concentration ..... 4.5.1. Maize Grain Mineral Nutrient Concentration ............. 4.5.2. Maize Leaf Mineral Nutrient Concentration ............. DISCUSSION ..................... 5.1. Bean Performance in the Two Cropping Systems 5.2. Bean Carbohydrate Concentration ........ 5.3. Performance of Maize in the Two Cropping Systems . . ................. 38 42 46 48 49 51 53 55 55 74 81 81 88 97 105 105 113 122 122 139 142 CHAPTER 5.4. Plant Nutrient Concentration ......... 5.4.1. Bean Nutrient Concentration ...... 5.4.2. Maize Nutrient Concentration ..... 6. SUMMARY AND CONCLUSION ............... APPENDIX A. ANALYSES 0F VARIANCE ................ B. CROP SCIENCE FIELD LAB RAINFALL DATA AT MICHIGAN STATE UNIVERSITY FARM, EAST LANSING ......... C. BEAN AND MAIZE SEED YIELDS ............. D. BEAN AND MAIZE 100-SEED WEIGHT ........... E. BIOLOGICAL (BIOMASS) YIELD (gm/m2) ......... F. MAIZE-BEAN LAND EQUIVALENT RATIOS (LER) ....... G. BEAN LEAF NUTRIENT CONCENTRATION .......... H. MAIZE LEAF NUTRIENT CONCENTRATION ......... I. BEAN SEED NUTRIENT CONCENTRATION .......... J. MAIZE SEED NUTRIENT CONCENTRATION .......... K. BEAN CARBOHYDRATE CONCENTRATION ........... L. GLUCOSE STANDARD SOLUTIONS ............. M. STARCH STANDARD SOLUTIONS .............. N. STANDARD CURVE FOR CARBOHYDRATE ANALYSIS ...... BIBLIOGRAPHY ........................ ix 157 157 159 163 172 186 187 193 196 197 198 204 210 216 222 228 229 230 231 TABLE 10. 11. LIST OF TABLES Effect of Year, Bean Cultivar, and Bean Density on Bean Yield and Yield-Related Traits in the Associated Culture ................. Effect of Bean Density on Dry Weight of Bean Cul- tivars in the Two Cropping Patterns ......... Effect of Year, Bean Cultivar, and Bean Density on Bean Yield and Yield-Related Traits in the Two Cropping Patterns .................. Effect of Year, Bean Cultivar, and Bean Density on Bean Carbohydrate Concentration during Mid-Pod Filling in the Associated Culture .......... Effect of Year, Bean Cultivar, and Bean Density on Bean Carbohydrate Concentration during Mid-Pod Filling in the Two Cropping Patterns ........ Effect of Year, Bean Cultivar, and Bean Density on Seed Nutrient Concentration of Bean in the Associated Culture ....................... Effect of Year, Bean Cultivar, and Bean Density on Seed Nutrient Concentration of Bean in the Two Cropping Patterns ................... Leaf Nutrient Concentration of Bean as Affected by Year, Bean Cultivar, and Bean Density in the Asso- ciated Culture .................... Leaf Nutrient Concentration of Bean as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns ................... Effect of Year, Bean Cultivar, and Bean Density on Maize Yield and Yield-Related Traits in the Associated Culture ........................ Effect of Year, Bean Cultivar, and Bean Density on Maize Yield and Yield-Related Traits in the Two Cropping Patterns ................... 56 62 69 75 78 82 85 93 98 102 TABLE 12. 13. 14. 15. 16.1. 16.2. 17.1 17.2 18.1 18.2 A1. A2. A3. A4. A5. Grain Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Asso- ciated Culture ................... Grain Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns .................. Leaf Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Asso- ciated Culture ................... Leaf Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns .................. Comparison of Carioca Traits in Monoculture and in Associated Culture ................. Comparison of Domino Traits in Monoculture and in Associated Culture ................. Comparison of Maize Traits in Monoculture and in Associated Culture--Maize/Domino Combinations . . . . Comparison of Maize Traits in Monoculture and in Associated Culture-~Maize/Carioca Combinations Three-Year Yield Average of Bean and Maize as Affected by Bean Density .............. Three-Year Protein Yield Average of Bean and Maize as Affected by Bean Density ............. Analysis of Variance of Bean Yield and Yield-Related Traits in the Associated Culture .......... Analysis of Variance of Bean Yield-Related Traits in the Associated Culture ............... Analysis of Variance of Seed Nutrient Yield of Bean in the Associated Culture .............. Effect of Year, Bean Cultivar, and Density on Carbo- hydrate Concentration during Mid-Pod Filling in the Associated Culture ................. Analysis of Variance of Seed Nutrient Concentration of Bean in the Associated Culture .......... xi 110 116 118 123 125 145 146 153 153 172 173 174 175 176 TABLE A6. A7. A8. A9. A10. Analysis of Variance of Leaf Nutrient Concentration of Bean in the Associated Culture .......... Analysis of Variance of Maize Yield and Yield-Related Traits in the Associated Culture .......... Analysis of Variance of Grain Nutrient Yield of _Maize in the Associated Culture ........... Analysis of Variance of Grain Nutrient Concentration of Maize in the Associated Culture ......... Analysis of Variance of Leaf Nutrient Concentration of Maize in the Associated Culture ......... xii 178 180 181 182 184 LIST OF FIGURES FIGURE 1. Stem Dry Weight of Bean at Different Reproductive Stages ....................... 64 2. Leaf Dry Weight of Bean at Different Reproductive Stages ....................... 65 3. Root Dry Weight of Bean at Different Reproductive Stages ....................... 66 4. Yield and Biomass of Bean at Different Densities . . 133 5. Yield and Pods of Bean at Different Densities . . . . 134 6. Yield and Leaf Area Index of Bean at Different Densities ...................... 135 7. Biomass and Pods of Bean at Different Densities . . . 136 8. Biomass and Leaf Area Index of Bean at Different Densities ...... , ................ 137 9. Yield of Bean and Maize at Different Densities . . . 147 10. Performance of Maize and Bean in the Two Cropping Systems ....................... 154 xiii CHAPTER 1 INTRODUCTION Bean production in Africa is concentrated in Eastern Africa, with about 61 percent of the total production divided equally among the five producers, Uganda, Rwanda, Kenya, Burundi, and Tanzania (Landano, 1980). Bean production in Tanzania is concentrated in the Arusha, Tanga, Kigoma, Mbeya, West Lake, Ruvuma, Morogoro, Iringa, Tabora, and Kilimanjaro regions. Arusha is the biggest bean producing region with an annual production of about 65,000 metric tons (Karel et al., 1980). Nearly all beans consumed in Tanzania are produced in associated culture. Bean yield ranges between 200 and 700 kg/ha (Jacobsen, 1976a). The low yields are associated with the low yield potential of the local cultivars, unfavourable weather, poor soil fertility and crop husbandry, and disease and pest infestation. In general, association Of beans with other crops also reduces seed yield. However, with improved cultivars, good crop husbandry, and better disease and pest control, up to 1,500 kg/ha can be harvested (Jacobsen, 1976a). Tanzania bean researchers reported bean seed yields of up to 3,000 kg/ha (Mmbaga et al., 1982). Associated culture often involves a cereal and a legume, with the cereal being considered the main crop (Nnko and Doto, 1982). Bean yields in associated culture are usually less than those obtained from sole bean stand. However, it is possible that yields could be increased with proper management practices such as the use of optimum density, improved bean cultivars, and disease and pest control. Bean yields in associated culture are a surplus to the main maize crop yield. Beans in Tanzania are generally produced and consumed locally as whole grain by both the rural and urban populations. Beans are usually boiled until soft, and cooked in accompaniment with maize, potatoes, cassava, and other kinds of food,eaten in Tanzania. Red or tan beans are preferred and when cooked look like small chunks of meat. Bean leaves are preferred in some parts of Tanzania and are fried or boiled and eaten as spinach. Dry beans are the most important grain legume crop and, like maize, beans constitute one of the staple foods in many parts of the country. High protein content of bean (18-32 percent) supple- ments that of non-legume food crops, thus minimizing malnutrition in the urban and rural communities. Bean protein partially replaces animal protein. The latter is not always available in sufficient quantity to the low-income sector of the population. Young, tender green bean leaves, green shelled seeds, and dry mature seeds provide daily protein, mineral nutrients, and vitamins for consumers. Increases in food production have not been able to keep pace with the rapid population growth, probably due to general poverty, unfavourable environment, and lack Of technology in developing countries. World food production has increased by 1.5 percent , while population has increased by nearly 3 percent annually (Steiner, 1984). Tanzania is no longer self-sufficient in food production and needs to import food at least in years when rainfall is insufficient. The rapid population growth has also caused land pressure in productive regions of the country. As a result, farmers are seriously constrained by land, labour, and capital. Consequently, intercropping of two or more crops in a given land area offers farmers the best option for sustaining their daily food supply. There is no indication of any decrease in the importance of mixed cropping. The system has evolved in different areas and is so deeply established among farmers that a complete change of the system may not be acceptable to most farmers. Greater biological efficiency and higher net income in some cereal—legume combinations suggest that the farmers with their limited resources are making a rational decision in maintaining their own mixed cropping system. However, improvement of the system is essential for the benefit Of those limited resource farmers who depend upon farming for their livelihood. Increasing food production by introducing new technologies relying on commercial inputs did not produce the expected results. The new methods were mainly adopted by a few large, rich farmers but hardly by the majority of the small-scale farmers who consti- tute about 90 percent of the farmers in Tanzania. Since land, labour, and capital are limited, it is highly unlikely that farmers will grow sole crop stands of maize and beans. As efforts to introduce sole cropping had often failed, it is currently a govern- mental policy to increase food production by improving the existing systems. A series of workshops on intercropping held at Morogoro, Tanzania (Keswani and Ndunguru, 1982; Monyo et al., 1976) empha- sized the willingness of the government to improve the associated culture system. It is hoped that improvement Of the intercropping system would result in surplus food crop production and consequently improve the standard of living of the community. Bean and maize are commonly desirable intercrop species because different growth rates and morphology of these crop species allow increased utiliza- tion of the environmental resources with minimum competition. Maize and bean in association provides a source of income, a balanced diet, and reduces labour peaks for farmers. It is worthwhile to develop cropping systems that have the capacity to maximize crop yield per unit land area while keeping fertilizer nitrogen applications to a minimum. Choice of com- patible component crops with diverse morphology, optimum crop density, optimum relative sowing time of component crops, and minimum crop competition will improve combined yields in associated culture. Intercropping intensifies crop production and may exploit environments with limiting or potentially limiting growth resources more efficiently (Papendick et al., 1976; Trenbath, 1982). Combinations of crops are determined primarily by the length of the growing season and the adaptation of crops to particular environments. In areas with annual rainfall of less than 600 mm and a short growing season, early-maturing and drought-tolerant crops such as millet and sorghum dominate (Andrews, 1972; Baker, 1979). In areas with annual rainfall more than 600 mm, cereals and legumes of varying maturities are used. In Central and South America, maize and different types of beans dominate the inter- cropping systems (Francis et al., 1976). Bean and maize seed and leaf protein, mineral nutrient, carbohydrate, and vitamin concen- trations usually determine the quality of human diets and livestock feeds. Intercropping has characteristics that would provide flexi- bility in crop combinations for farmers. If appropriate technolo- gies can be developed to exploit the potential of associated cul- ture, farmers could become self-sufficient in food production. The objective of this experiment was to determine the optimum bean density that would accumulate adequate dry weight during the vegetative phase in order to increase seed yield in associated culture. The ultimate aim was to improve farmers' benefits from the cropping system. This study was undertaken to determine: (1) Optimum bean density combinations with maize (40,000 plants/ha) that are capable of early storage of adequate dry weight before the peak competition from maize. If the combined yield of the component crops in associated culture will be higher than monocultural component crops or higher than the best monocultural crop species yield due to more efficient utilization of natural resources. CHAPTER 2 REVIEW OF THE LITERATURE 2.1. Bean Seed Yield and Yield-Related Traits 2.1.1. Bean Seed Yield in Association Productivity in associated culture is increased due to phase differences in periods of peak demand for natural resources (Steiner, 1984) and improved water use efficiency by the component crops (Mkandawire, 1987). Associated culture persisted for many years due to increased yield stability, reduced disease and insect risks, better utililization of labour, and high productivity per unit land area (Andrews and Kassam, 1976). Maximum productivity in an intercropping system is achieved when inter- and intra-crop competition is minimized for growth-limiting factors and the density of each crop is adjusted to minimize competition between the crop species (Huxley and Maingu, 1978). Cereals have stronger competitive ability than the _Companion legume even though the density of the legume may be greater than that of cereals (0siru and Willey, 1972). Yield potentials of Climbing beans (4 tons/ha) and bush beans (3 tons/ha) in monoculture were reduced to a common level of one ton per hectare when associated with maize (Clark and Francis, 1985). Beans in association produced only 25-60 percent of their monocultural yield potential at comparable bean densities (Francis et al., 1976). Mmbaga (1980) observed seed yield of bean in associated culture ranging from 34 to 55 percent of their seed yield under monoculture at East Lansing, Michigan. In Kenya, Hasselbach and Ndagwa (1982) observed that 43 percent of bean seed yield reduction was attributed to interplanted maize. Maize-bean association in Malawi resulted in 51 percent bean yield reduction and 44 percent maize yield reduction (Edje and Laing, 1982). Bean seed yields improved with an increase in planting densities. Bean yields were strongly affected by maize competition. The relationship between the yields of climbing bean culti- vars and maize when intercropped was inverse. Climbing bean yield potential was associated with a longer life cycle than bush beans. It is also associated with prolonged durations of both leaf area and podfilling. The bean yield loss in associated culture was attributed to greater overlap with the dominant maize which reduced leaf area and podfilling phases (Clark and Francis, 1985). Dura- tions of both phases were equal when bush and climbing beans were intercropped and final yield differences between them were not sig- nificant. The most competitive bean cultivars were the highest yielding in association and were tall, more vigorous, and later to mature. Likewise, the most competitive maize genotypes were also tall plant types (Davis and Garcia, 1983). Breeding beans with physiological tolerance to shade particularly after flowering and with enhanced nitrogen fixation would improve seed yield in asso- ciated culture (Davis and Garcia, 1983). Early maturing beans maintained better yields in association with maize than medium- or late-maturing cultivars. In the medium- and late-maturing beans there was substantial yield reduction (Osiru, 1982). A suitable cultivar for maize/bean association would be one that utilizes available resources and matures early. It should be fairly erect and indeterminate with short vine to ensure maximum competition with maize during the early part of the season (Osiru, 1982). This observation supports an increased emphasis on early pod set and seed filling in bean genotypes for simultaneously planted bean-maize intercrops. Yield potential is most likely to be reached when component crOpS make their major resource demands at different times (Francis, 1978). Bush beans under severe competition are very efficient in use of scarce resources. Maize-bean intercropping results in lower soil moisture than when beans are grown in pure stand (Mkandawire, 1987). Consequently, seed yields of bean in associated culture were usually lower than seed yield under monoculture. Bean yield in maize-bean association decreased mainly due to a reduction in the number of pods per plant (Gardiner and Craker, 1981). Francis et al. (1976) explained the reduction in terms Of a reduction in number of racemes per plant, and lower pod and stem weights per plant. . Maize competition for resources is higher than that of beans. Yields of maize under optimum density and management conditions were often not affected when intercropped simultaneously with the 10 common bean (Mmbaga, 1980; Mmbaga et al., 1982). Any reduction that might occur was normally substantially less than the observed bean yield (Davis and Garcia, 1983). However, bean yield might strongly be affected by maize competition (Francis et al., 1982). Fertilization with 60-70-30 for maize and 20-35-15 NPK for bean, respectively, produced a high combined yield of both maize and beans (Oliveira et al., 1983). Maize competition also reduced bean components of yield in all four bean cultivars (Francis et al., 1982). The absence of specific maize cultivar x bean cultivar interactions indicated that bean cultivars selected with any particular maize genotype should be equally suitable for planting with any other maize genotypes (Davis and Garcia, 1983). Francis (1978) suggested that near simultaneous planting was optimal for production of the highest total yield from intercropped maize and beans. Estimates from Latin America suggested that about 60 percent of maize and 80 per- cent of beans were produced in associated culture (Francis, 1978). 2.1.2. Harvest Index Harvest index is the ratio Of seed weight to total plant biomass and is commonly used as an index of the proportion of assimilates allocated to a specific sink of a plant. It is cur- rently used to evaluate cultivars' partitioning efficiency. Harvest indices of the common bean vary for different cultivars and growing conditions. Wallace et al. (1972) reported harvest indices from 53 to 67 percent among eleven cultivars of common bean. These 11 values reflected the fact that in measurement of the harvest index of grain legumes, leaves are generally not included because they are lost before harvest. Cultivars with the highest harvest index had the lowest seed yield (Wallace and Munger, 1966). Standardized correlated responses to selection for grain yield through the harvest index of individual F2 plants showed that harvest index was of limited value for yield improvement (Zimmer- mann et al., 1984). Mmbaga (1980) obtained harvest index values ranging from 62 to 65 percent in a monoculture/intercropping experiment. In general, the lines with some ability to climb suffered less reduction in harvest index than the bush type due to competition for light from the maize (Davis et al., 1984). 2.1.3. Dry Weight Distribution Dry weight distribution among plant organs in plants har- vested sequentially suggested a movement of assimilates from leaves to stem and then to pods (Burga, 1978). Dry weight distribution in leaves, stems, and pods of beans in monoculture at 58 days after planting (DAP) was 41, 33, and 4 percent, respectively. However, in bean-maize associations, bean dry matter distribution for leaves, stem, and pods of beans was 33, 45, and 2 percent, respec- tively, for the same period (Edje and Laing, 1982). Bean and maize growth cycles are usually offset in time; bean growth significantly exceeded maize growth during the first 26 days (Clark and Francis, 1985). Maize dry matter (0M) significantly exceeded that of the bean after 47 days but nitrogen content did not differ consistently 12 between the bean and maize monocrOps after 33 days (Clark and Francis, 1985). The staggering of planting and hence growth cycles in the bean-maize intercrops may result in significantly more dry matter, nitrogen, and leaf area index (LAI) than either component monocrop during all or part of the growing season. Seed filling in common bean is sustained by on-going photo- synthesis, mobilization of starch from leaf tissue, and possibly the remobilization of stored root and stem assimilates (Burga, 1978; Bouslama, 1977; Lindoo and Nooden, 1976). Stored carbo- hydrate could serve as a buffer to support normal grain growth despite adverse weather conditions (Yoshida, 1972). Soybean seed growth rates were not Closely related to rates of photosynthate production because storage carbohydrate acted as a buffer between seed growth and photosynthesis (Egli and Legget, 1976). Yield superiority in the architype (indeterminate type 11 growth habit, few branches with a narrow erect profile, and a long seed filling period) is based on extended filling periods, high partitioning and remobilization of carbohydrates and nitrogen, large sink, and lower abscission rate (Izquierdo, 1981). Remobili- zation of reserve from storage sites Optimized and stabilized yields in dry beans. Late remobilization of carbohydrate reserves can be triggered by stress conditions and thus stabilize yield (Izquierdo, 1981). Bush beans are characterized by a short but rapid filling period, high partitioning, and high remobilization (Izquierdo, 1981). Once the photosynthetic mechanism becomes 13 impaired, bush bean pod filling is dependent on remobilization (Izquierdo, 1981). Stems and pod walls were the most important sources of remobilizable reserves (Izquierdo, 1981). Nep-2 and Black Turtle varieties maintained a high amount of accumulated starch and nitrogen in stems at physiological maturity (Izquierdo, 1981). High root and stem starch content throughout the reproductive stage was associated with low-yielding cultivars. This accumulation of Starch in stems during pod-filling indicated that beans were inefficient in their use of photosynthate or pro- vided inadequate sink capacity for the present resources (Adams et al., 1978; Biddulph and Cory, 1965). Some evidence suggested that yields in grain legumes are source limited (Sinclair and de Wit, 1975). Tanaka and Fujita (1979) reported that during the most active period of flowering and pod wall growth the carbohydrate content of stems was low. This indicated that the sink capacity exceeded the source capacity during the period of peak demand. Consequently, source may be a limiting factor during the flowering and pod wall growth period (before actual seed filling), resulting in flower and/or pod abortion. Tanaka and Fujita (1979) considered the abortion of excessive flowers and pods as a unique characteristic of dry beans to adjust the sink size to the source in order to keep seed size relatively stable (yield component compensation). Starch concentration in the lower stem with few pods increased continuously from flowering but in other plant parts 14 declined after early pod filling. Starch accumulation increased from anthesis and was maximum at the mid-seed filling stages in roots, stem, petioles, and pod wall (Izquierdo, 1981). Concentra- tion of .soluble sugars in nodules and roots declined at mid pod- fill. Nitrogen fixation decreased rapidly after peaking at early pod-fill, reaching the lowest value at mid pod-fill. The decline was accompanied by the loss of lower leaves and the presence of a high concentration of starch in the stem (Waters et al., 1980). Bean leaves on lower nodes are the major contributors of photosynthate to roots and lower stem sections (Biddulph and Cory, 1965; Lucas at al., 1976; Wien et al., 1976). Since canopy Closure reduces light penetration to the lower levels of the crop profile, the dependence of nodules on photosynthate from lower leaves could be a major factor limiting N2 fixation (Waters et al., 1980). High plant density greatly reduced N2 fixation of individual bean plants (Graham and Rosas, 1978). The availability of photosynthate to below-ground parts also depended on competition from more active sinks higher up the plant (Lawrie and Wheeler, 1974; Lucas et al., 1976). Yield differences among cultivars were associated with the length of the seed filling period rather than with the rate of seed growth (Izquierdo, 1981). The seed filling duration was correlated with yield and days to maturity, suggesting that a short reproduc- tive period might result in a reduction in yield (Tohme, 1986). Type II beans showed more than a two-fold increase in the duration 15 of the filling period when compared with the bush bean cultivars (Izquierdo, 1981). Genetic differences in accumulation and deple- tion of stem reserves among bean cultivars were reported by Adams et al. (1978). They reported starch values ranging from undetect- able to abundant amount in roots and stems of twenty-three dry bean cultivars. Starch amount varied with the three physiological stages (flowering, mid pod-filling, and physiological maturity) at which samples were taken. In addition, they found no clear pattern of relationship between starch accumulation in stems and roots and yield. Prior to flowering, in experiments conducted by Waters et al. (1980), over 85 percent of the recovered C14 activity translocated from node four was in roots, nodules, and lower stem. However, at flowering, radioactivity translocated to the lower stem declined but correspondingly increased in nodules (Waters et al., 1980). Nodules accumulated only 3.5 percent of the radioactivity of the preflowering stage. Westermann et al. (1985) observed that seed at physiological maturity contained 64, 73, and 84 percent of the labeled-N applied at the late vegetative, early pod development and seed filling stages, respectively. The seed contained an average of 68 percent of the total plant N and 53 percent of the total plant dry weight at physiological maturity (Westermann et al., 1985). Consequently, photosynthetic and Nz-fixation activities during seed filling could 15 have a significant influence on the final seed N concentration and bean seed yield (Westermann et al., 1985). 2.1.4. Leaf Area Maize reduced maximal bean leaf area index (LAI) in the bush and climbing cultivars. Reduced LAI was noted at 40 days in the bush bean but not until 54 days in the climbing bean (Clark and Francis, 1985). In the bush bean, intercropping had no effect on the duration of leaf area expansion, while in the intercropped climbing bean leaf area expansion was curtailed at forty-seven days (Clark and Francis, 1985). Leaf area indices of the two monocrop bean cultivars were nearly identical up to 47 days, after which the bush bean declined (Clark and Francis, 1985). This reflected the shorter life cycle of the bush bean while the Climbing bean continued to increase to a maximal LAI at 60 days (Clark and Francis, 1985). In Kenya, maximum leaf area indices Of 3.2, 3.2, and 4.8 were obtained from Rose Coco, Mweze Moja, and Canadian Wonder, respectively (Coulson, 1985). Yamaguchi (1974) showed that leaf area index was the trait most associated with grain yield and was positively correlated with number of leaves per plant, plant height, and lodging susceptibility. 17 2.2. Maize Yield and Yield Components 2.2.1. Grain Yield Maize yields are often not affected when intercropped with common beans under optimum management conditions and moderate densities (Francis, 1978a). The findings indicated that neither competitive depression nor nitrogen transfer from the legume occurred (Searle et al., 1981). Intercropping depressed legume dry matter and grain yield at 0 kg N ha-1 (Francis, 1978a). Maize yield reduction depends on the competitive ability of common bean cultivars used in association with maize (Davis and Garcia, 1983). Yields of maize in the tropics are generally lower than those reported from temperate environments due to lower harvest indices (30-40 percent) as compared with 50-55 percent for temperate germ plasm (Goldsworthy, 1974; Daynard, 1969). This is possibly due to more suitable growing conditions in the temperates such as longer daylight and cooler nights for maize as compared to the tropics. Seed yield from maize may be a function of the rate and duration of dry matter accumulation by the individual kernels multiplied by the number of kernels per plant (Poneleit and Egli, 1979). Studies have Shown positive association of the duration of grain dry matter accumulation with yield per unit area (Daynard and Kannenberg, 1976). 2.2.2. Land Equivalent Ratio The concept of a land equivalent ratio (LER) has been used to obtain evidence as to whether two or more crops should be 18 intercropped rather than planted as sole crop stands (IRRI, 1974). LER is the most frequently used index to determine the effective- ness of intercropping relative to growing crops separately (Willey, 1985). LER is defined as the total land area required under sole cropping to give the yields obtained in the intercropping mixture. It is expressed as: LER = Yij/Yii + in/ij where Y is the yield per unit area, Y1; and ij are sole crop yields of the component crops i and j, and Yij and in are inter- crOp yields (Mead and Willey, 1980). The partial LER values, L1 and Lj, represent the ratios of the yields of crops i and j when grown as intercrops relative to sole crops. Thus L1 = (Yij/Yii) and Lj = (ij/ij) . LER is the sum Of the two partial land equivalent ratios so that LER = Li + Lj . The partial LER values give an indication of the relative competi- tive abilities of the components of intercrop systems. The value of LER is determined by several factors including density and competitive ability of the component crops in the mixture, spatial arrangement, crop morphology and duration, and management variables that affect individual crop species (Enyi, 1973; Natarajan and Willey, 1980a; Fawusi et al., 1982). It was suggested that in 19 density studies of cereal-legume intercrop systems, the sole crop yields used as standardization factors for estimating LER should be at the optimum densities of the crOps (IRRI, 1974; Huxley and Maingu, 1978). The values of LER follow the density of the legume component rather than that of the cereal (Ofori and Stern, 1987) and possibly the trend of the competitive gap. Differences in growth durations of component crops affect the magnitude of the LER. The LER values in crops with similar maturi- ties are usually less than in crop combinations with contrasting maturities (Trenbath, 1976; Willey, 1979). No yield advantages were found in maize-cowpea (Haizel, 1974) and sorghum-cowpea (Andrews, 1972; Rees, 1986) intercrop systems in which components were of similar growth durations and consequently narrowed competi- tive gap. Enyi (1973) studied maize or sorghum intercropped with either cowpea or beans of similar growth durations and observed that productivity was less than when compared to intercropping of these cereals with 240-day pigeon pea. The estimated partial LER of maize was 0.72 with pigeon pea, 0.64 with beans, and 0.50 with cowpea. The lower partial LER values for the associations with beans and cowpea may be due to competition in the intercrop state for growth-limiting factors, because peak demands on the environ- ment by these crops might have coincided with those of the cereals. The availability of water also appeared to influence the LER. In maize-bean (Fisher, 1977) and sorghum-cowpea intercrop systems (Mafra et al., 1981; Rees, 1986), LER values increased with the 20 availability of water and diminished when water was limited. However, Natarajan and Willey (1980b) noted that LER increased under limited water situations. The cereal component with rela- tively high growth rate, height advantage, and a more extensive rooting system is favoured in the competition with the associated legume. The yield of the legume component declined on average by about 52 percent of the sole crop yield, whereas the cereal yield was reduced by only 11 percent (0fori and Stern, 1987). Biological efficiency as measured by the land equivalent ratio was higher in intercrop than in monoculture, and one inter- crop combination showed a 65 percent advantage over monoculture (Francis et al., 1982). Mmbaga et al. (1982) obtained LER values of 1.25 and 0.96 when maize was intercropped with bean exhibiting types I and III, respectively. Edje and Laing (1982) in Malawi observed a land equivalent ratio greater than unity while Mmbaga (1980) at East Lansing, Michigan, obtained LER values of up to 1.34 when type II was intercropped with maize. Total grain yields of maize and bean did not show any advantage for either monoculture or intercropping at higher maize densities (Francis et al., 1982). Land equivalent ratio can be greater than 1.0 if mixtures are less affected by pests and/or diseases than sole crop stands, or if the two crops do not compete seriously for one or more environ- mental resources (Trenbath, 1976). Less competition could occur if the crops use different forms of a given resource that are avail- able, if they use the same resource at different times or from 21 different zones of the environment, or if quantities available are in excess of requirements (Trenbath, 1976). 2.3. Light Interception in the Two Cropping Systems Light cannot be influenced directly by man as is the case with moisture and nutrients, and therefore often becomes the limiting factor. Legumes are commonly grown in the tropics under reduced solar radiation due to dense cloud cover and shading from tall intercrops (Eriksen and Whitney, 1984). Photosynthetic response of a plant is affected by the light intensity at which it is grown (Wolf and Blaser, 1972). High intensity radiation induced additional development of the palisade and spongy mesophyll regions, resulting in thicker leaves (Pearce and Lee, 1969). Intercropped beans developed thinner leaves characteristic of plants under reduced light intensity (Crookston and Hill, 1979). Maize canopy apparently contributed to more light intercep- tion and less light reflection in the intercropped beans. Strong correlations exist between the yield Of a crop and its light environment (Shibles and Weber, 1965). Considerable attention has therefore been given to optimizing crop leaf area index and to designing plants which permit maximum light penetration into the lower canopy (Wilfong et al., 1967). A photomorphogenic effect which stimulated some bean genotypes to Climb was described by Kretchmer et al. (1979). The stimulus to climb may be related to the quality of light penetrating through the maize canopy (Kretch- mer et al., 1979). Photosynthetic energy transmitted to the ground 22 before attainment of full cover in a row monocrop represents a wasted resource (Clark and Francis, 1985). The utilization of this resource by an interplanted crop may increase total resource use by the intercrop (de Wit, 1960). Shading of legumes generally caused elongated growth, reduced specific leaf weight (SLW), and increased leaf area per unit of plant weight (Beuerlein and Pendleton, 1971). Shading did not affect plant heights of cowpea and bush beans except for some petiole elongation in bush beans (Eriksen and Whitney, 1984). Number of seeds per pod was unaffected by shading in cowpea, soybean, and bush bean. Cowpea was the most shade sensitive, soybean was intermediate, and bush bean was least sensitive (Erik- sen and Whitney, 1984). Shading of beans by maize plants during the later growth stages probably reduced the supply of photosynthate for the developing seeds (Fisher, 1979) and contributed substantially to the decreased yields of bean plants in the associated culture. Shading appeared to be the main competitive effect of maize on beans (Zelitch, 1971). A reduction of photosynthetically active radiation (PAR) incident on bean canopies reduced bean yield, growth rate, LAI and net assimilation rate (Gardiner and Craker, 1981), leaf number, area, and thickness, and pod number (CIAT, 1976; Crookston and Hill, 1979). Photosynthesis per unit area of shaded leaves was decreased by an average of 38 percent (Crookston, 1975), while transpiration was not significantly affected. 23 Increased intracellular resistance of the shaded leaves was more important in reducing C02 uptake than was the increase in stomatal resistance (Crookston, 1975). In experiments conducted by Burga (1978), shade environment reduced the C02 uptake rates of Seafarer and Nep-2 by 55 and 30 percent, respectively. Shade also reduced the amount of starch in stem (Burga, 1978). Knecht and O'Leary (1972) indicated that there is a decrease in the size and/or number of stomata per unit leaf area Of shaded leaves, with a resultant increase in leaf resistance to C02 diffusion. Shading consistently resulted in thinner and frequently smaller leaves, thus reducing the volume of photosynthetic cells per leaf or per unit leaf area (Wilson and Cooper, 1960). Light interception by maize leaves was quite small until late in the life of the bean crop (Fisher, 1979). Light interception by maize rose steadily up to about 79 days from emergence and then maintained a value between 60 and 70 percent until 132 days (Fisher, 1979). Fisher (1979) proposed that bean yield reductions under maize were due to root competition since bean plants reached their peak light interception early in the growing season before the maize canopy had developed. More than 90 percent light penetrated the mixture until about 53 days after planting (DAP) (Fisher, 1979). Light penetration to the beans declined from 90 to 67 percent at 71 DAP (Fisher, 1979). Beans reached peak interception at about 36 DAP. Maize and beans in mixtures had higher mean seed weights 24 than in sole crop stands, though not significant (Fisher, 1979). This is a common phenomenon in mixed cropping, attributed to relaxation of competitive stress on one or more of the species during its grain filling phase where these are separated in time and competitive gap (de Wit, 1960). The rate of dry matter production in crops depends on the efficiency of the interception of photosynthetically active radiation (PAR) (Biscoe and Gallagher, 1977; Monteith, 1977). The generally taller cereal shades the legume, and at high densities causes reduced growth and yield of the companion legume. Gardiner and Craker (1981), maintaining a constant bean density of 220,000 plants/ha, found that varying maize density from 18,000 to 55,000 plants/ha progressively reduced the amount of light available to the beans. At the low maize density (18,000” plants/ha), beans received 50 percent of the incident light, compared to 20 percent at the highest maize density (55,000 plants/ha). At the highest maize density, yield of the intercrop bean was only 30 percent that of the bean in monoculture. Light interception in maize-pigeon pea intercrop was low with the initial Slow increase in leaf area index (LAI), and about 80 percent when LAI reached about three (Sirakumar and Virmani, 1980). The foliage canopy of the intercrop was more effective in capturing the light. Maize-pigeon pea intercrop attained an LAI of three in 45 days, compared to 50 days in the sole maize and 115 days in the sole pigeon pea. Sirakumar and Virmani (1980) observed that dry matter production per unit of PAR 25 absorbed was higher in the maize-pigeon pea mixture than in the sole crops. 2.4. Water Use in the Cropping Systems Water is the most important soil factor in semiarid and sub- tropical regions where inadequate rainfall may frequently limit crop production (Baker and Norman, 1975). The differences in root systems, depth of rooting, lateral root spread, and root density are factors that affect competition for water between component crops (Babalola, 1980; Haynes, 1980). The use of different parts of the soil profile by root systems of different crop species minimizes the degree Of competition for water (Haynes, 1980). The cereal is generally favoured when component crops compete for available water due to its higher growth rate and more exten- sive root system. The total water use by sole pigeon pea at the end of the growing period (173 DAP) was 584 mm and in the mixture was 585 mm; in sole sorghum at harvest (82 DAP) it was 434 mm. Reddy and Willey (1981) obtained a total water use Of 406 mm in the mixture, compared to 303 mm in sole millet (82 DAP) and 368 mm in sole groundnut (105 DAP). Hulugalle and Lal (1986) reported that water use efficiency (WUE) in maize-cowpea intercrop was higher than that in the sole crops when soil water was not limiting. However, under drought conditions WUE in the intercrop was lower compared to the sole maize. For the favourable moisture regimes, WUE (kg grain/mm/ha) of the intercrop was 3.6 compared to 2.1 in eight of the sole 26 crops, and for the droughty conditions, 1.6 for the intercrop, 2.2 for the sole maize, and 0.5 for the sole cowpea. 2.5. Management Factors Influencing Productivity and Efficiency in the Two Cropping Systems 2.5.1. Component Crop Density In a maize-bean intercrop system increasing maize density three-fold, from 18,000 to 55,000 plants/ha, caused reductions of 24 percent in leaf area index and 70 percent in seed yield of the associated bean (Gardiner and Craker, 1981). Density of the cereal component contributes a greater proportion to mixture yield, but the efficiency of the cereal-legume intercropping systems, measured in terms of LER, follows the trend of the intercrop legume com- ponent yields (Natarajan and Willey, 1981a). Seed production of component crops in an intercropping pattern is determined by such factors as density of seeding Of each component, relative competitive ability, plant height, cycles of maturity, and genotypes (Francis et al., 1982). There is a range of successful plant density levels in the maize-bean association which may be used to attain maximum grain and protein yield and net income. Research in bush bean monoculture has shown a yield plateau for densities greater than twenty plants/m2 (CIAT, 1975), and the density needed to reach this plateau was unrelated to bean cultivar (Francis et al., 1982). Maize density appeared to influence both maize and bean yields and yield components to a much greater degree than inter- 2.7 cropped bean density (Francis et al., 1982). Maize is taller and shades the developing bean crop. However, a vigorous intercropped climbing bean may reduce maize yield (Francis et al., 1982). Maize yields were positively correlated with maize density and ears per plant. Bean seed yield was positively correlated with pods/m2 and pods/plant, but not with bean density (Francis et al., 1982). Reductions in leaf area index, growth rate, and net assimilation rate of beans occurred under high maize density as compared with bean monocrop (Gardiner and Craker, 1981). 2.5.2. Plant Configuration and Spacing Row arrangements, in contrast to arrangements of component crops within rows, improved the amount of light transmitted to the lower legume canopy. Such arrangements can enhance legume yields and efficiency in cereal legume intercrop systems (Mohta and De, 1980). In a maize-groundnut intercrop system Evans (1960) obtained LERs of 1.09 in the same row arrangement compared to 1.30 in alternate rows. In the maize-pigeon pea system, maize yield was not affected in the alternate row arrangement, but it was reduced by 20 percent when the pigeon pea was in the same row (Dalal, 1974). Consequently, arrangement of component crops in alternate rows is more beneficial than in the same rows. In contrast to these observations, Agboola and Fayemi (1971) did not observe any difference whether maize and cowpea were planted in the same or alternate rows. The use of double rather than single alternate row arrangements of component crops improved the yield, light 28 penetration to the canopy of the legume component, and efficiency of the intercrop pattern. 2.5.3. Time of Sowing The relative time of sowing of component crops is an impor- tant management variable manipulated in cereal-legume intercrop systems. Andrews (1972) pointed out that differential sowing improved productivity and minimized competition for growth-limiting factors in intercropping. Willey (1979) also pointed out that sowing component crops at different times ensured full utilization of growth factors because crops occupy the land throughout the growing season. In contrast to simultaneous sowing, maize sown five to fifteen days earlier than beans increased maize yields by 13-43 percent and the associated bean yields were reduced by 20- 27 percent (Francis et al., 1976). On average, intercropping effi- ciency measured as LER was 39 percent higher when beans were sown 5-15 days before maize. Studies on maize intercropped with four contrasting bean cultivars sown 5-10 days apart suggested that near-simultaneous sowing of component crops was optimal for attain- ing the highest combined yields and intercropping efficiencies (Francis, 1978; Francis et al., 1982a). In Colombia, Francis et al. (1982b) varied dates of sowing maize and indeterminate beans (types 11 and III) and noted that maize was more competitive than beans at all sowing dates, except when beans were sown 10 days earlier. Sowing maize 10 days before beans reduced bean yield by 69 percent and maize by only 7 percent. 29 Beans sown 10 days earlier reduced maize yield by 53 percent and bean yield by 21 percent. In Nigeria, Remison (1982) did not find any advantage of staggered over simultaneous sowing dates of maize and cowpea. Intercropped cowpea yield was reduced by 57 percent and maize yield by 35 percent when sown Simultaneously. In Western Australia, Ofori and Stern (1987) concluded from a maize-cowpea intercrop system that staggered sowing dates of component crops at intervals of 10 or 21 days were of no advantage over sowing them simultaneously. May (1982) observed that a yield advantage of 32 percent completely disappeared when green-gram was sown one week after bulrush millet. From these studies, it may be concluded that staggered or differential sowing of component crops is of no advantage over simultaneous sowing. In staggered sowing, the earlier sown component has an initial advantage over the later sown component. Component crOps are unable to compensate fully for yield loss due to earlier or later association with the other component. 2.6. Pest Interactions in the Two Cropping Systems The environment of the bean plant is drastically changed by intercropping and therefore diseases and insects may form a major constraint for bean production. Intercrops generally suffer less disease attack than monocultural crops with the same overall density. Mixed stands contain a greater proportion of plants with resistance to some of the pathogens present (Steiner, 1984). The total plant density of intercrops is mostly higher than that of 30 either sole crap. This induces a change of microclimate, espe- cially where low-growing crops are interplanted between tall species (shelter effect) (Burdon, 1978). Van Rheenen et al. (1982) observed that beans grown in association with maize showed a lower incidence of halo blight, bean common mosaic virus, anthracnose, common blight, scab, mildew, and to a lesser extent angular leaf spot. The opposite was observed with white mold (van Rheenen et al., 1982). Relative humidity in mixtures is generally increased and becomes more favourable for some fungal and bacterial diseases (Burdon, 1978). The susceptibility of the crop species, primarily the dominated ones, might also increase due to reduced insolation (Burdon, 1978). Associated culture may restrict early development of dominated crops, making them more susceptible to disease (Burdon, 1978). Ascochyta phaseolerum was less prevalent in cowpea inter- planted with maize than in cowpea growing alone. The total number of diseased plants as well as the speed of dissemination of the pathogen was less in the polyculture (Larios and Moreno, 1977). The total number of infected plants with cowpea mosaic virus (CPMV) and chlorotic cowpea mosaic virus (CCMV) was lower in polyculture than in monoculture, apparently because fewer numbers of vector Chrysomelid beetles (e.g. Diabrotica cerotoma) were present in the mixed stands. A similar situation occurred in Malawi where beans trapped aphids, thus decreasing the Spread Of rosette disease of groundnut in mixed stands (Thresh, 1982). Pigeon pea in Haiti was 31 completely protected from virus diseases when grown between rows of tall sorghum (Palti, 1981). On the other hand, the severity of angular leaf spot of beans caused by Isariopsis griseola was highest in bean polycultures that included maize and lowest in systems where beans were intercropped with sweet potatoes or cassava (Moreno, 1977). Some crop associations modify the microclimate and result in increased relative humidity and shade. Consequences of the modi- fied microclimate may favour the incidence of diseases such as angular leaf spot and wilt of the common bean. However, the shielding effect of the companion crops against airborne pathogens should more than offset the microclimatic advantage pathogens may derive from the dense foliage of mixed crops (Palti, 1981). Mix- tures of different crop species buffer against disease losses by delaying the onset of the disease, reducing spore dissemination, and/or modifying microenvironmental conditions such as humidity, light, temperature, and air movement. Certain associated plants can function as repellants, antifeedants, growth disrupters, or toxicants. Some plant combinations may enhance soil fungistasis and antibiosis through indirect effects on soil organic matter content (Sumner et al., 1981). The use Of interspecific mixtures and therefore a higher level of diversity of genotypes shows great possibilities for disease reduction. A parallel approach involves the use of multilines in cereal crops to achieve high genetic diversity (Browning, 1975). 32 Intercropping systems enable farmers to spread the risk of crop losses due to insect attack (Steiner, 1984). Farmers, through intercropping, created an unsuitable habitat for some pests and a favourable environment for predators (Steiner, 1984). Con- sequently, complexity of plants in associated culture led to a lower buildup of insects than when crops were grown in sole crop stands. The dispersal of both the adult and larvae stages of insects may be impeded where host and non-host are growing together. The resistant or non-host plants may offer a barrier to the dispersal of inoculum or pests (Burdon, 1978) leading to less bean damage. Maize in maize-groundnut intercrop is attacked less fre- quently by the maize borer because the borer moth prefers a background with a brownish colour to a solid green background (Raros, 1973). In addition, some pests avoid their preferred crops when shaded by taller crops in association (Karel, 1982). Intercropping does not necessarily favour only predators; there are examples where it favours pests, too. The attack on cotton by the American boll weevil was increased by relay-inter- cropping maize with cotton (Steiner, 1984). The foliage beetle, Ootheca mutabilis, caused significantly more damage in mixed crop cowpea than in sole crop (IITA, 1978). Pigeon pea is highly attractive to thrips, a major cowpea pest. Thrips damage to cowpea is therefore increased in the vicinity of pigeon pea (IITA, 1978). Ecologists have conducted experiments in multiple cropping systems 33 to test the theory that increased plant diversity fosters stability of insect populations (Pimentel, 1961; Root, 1973). Examination Of 198 herbivore species showed that 53 percent exhibited lower abun- dance in multicrops than in monoculture, 18 percent were more abundant in multicrops, 9 percent showed no difference, and 20 per- cent showed a variable response (Andow, 1983; Risch et al., 1983). In Nigeria, populations of flower thrips were reduced by 42 percent on cowpea/maize polyculture. However, cropping pattern had no effect on infestations of Maruca testulatis, pod-sucking bugs, and meloid beetles (Matteson et al., 1984). Early infestations of Mgrgga were no different in monocrops and polycultures of maize and cowpea in Nigeria, but 12 weeks after planting infestations were significantly higher in the monocrops. Similar shifts were observed with thrips (Matteson et al., 1984). In India, larval populations of Heliothis amigera were higher in sorghum-pigeon pea intercropping systems than in sole crop pigeon pea plots, which led to high grain losses in polycrops (Bhatnagar and Davies, 1981). In the Philippines, Hasse and Litsinger (1981) observed that inter- cropping maize with legumes did not reduce the numbers of egg masses laid by common corn borers (Ostrinnia furnaealis). A reduced insect pest incidence in multicrops may be the result of increased parasitic and predator populations, decreased colonization and reproduction of pests, chemical repellency, masking and/or feeding inhibition from non-host plants, and preven- tion of pest movement and/or emigration (Matteson et al., 1984). A 34 host plant may be protected from insect pests by the physical presence of other overlapping plants. A case in point is the camouflage of bean seedlings by standing rice stubble for beansfly (Hasse and Litsinger, 1981). Certain pests prefer a crop back- ground of a particular colour and/or texture. Aphids and flea beetles are more attracted to sole crops with a background of bare soil than to ones with a weedy background. Aromatic odors of certain plants can disrupt host finding behavior. Grass borders repelled leafhoppers in beans and population of Plutella xylostella are repelled from cabbage-tomato intercrops (Hasse and Litsinger, 1981). Risch (1981) looked at the population dynamics of six Chrysomelid beetles in monocultures and polycultures of maize-bean- squash. In polycultures containing at least maize, the number of beetles per unit was significantly lower relative to the numbers of beetles on host plants in monocultures. Beetles tended to emigrate more from polycultures than from host monocultures due to shade and barrier to beetle movement. Egunjobi (1984) studied the ecology of Pratylenchus brachyurus in traditional maize cropping systems of Nigeria. Nitrogen, phosphorus, and potassium fertilizer applica- tions increased the numbers of the nematode more in\ soil under monocultural maize than in plots with maize intercropped with cowpea, groundnut, or green gram. Intercropping can suppress the growth of weeds more than sole cropping if interference between crop components is weaker than that between crops and weeds (Yih, 1982). Intercrops were better 35 at suppressing weeds within 30 days after sowing because of increased preemptive use of light effected by earlier canopy closure (Bantilan et al., 1974). The role of allelochemical interference between intercrop components and weeds has scarcely been explored. This type of weed control was potentially useful in monoculture cropping systems (Putnam and Duke, 1974; Fay and Duke, 1977; Lockerman and Putnam, 1979). In intercrops, there must be selectivity in the effects of toxins released by the crops; weeds must be more susceptible than crop components. Gliessman (1983) evaluated the effect of squash leaf extract on radical elongation of maize, cowpea, and cabbage seedlings. The extract had a stronger inhibitory effect on cabbage than on the other two species. Shading combined with selective allelochemical produced by the squash leaves can be an effective means of weed control in maize-cowpea polyculture (Gliessman et al., 1981; Letourneau, 1983). Intercrops are generally more effective in reducing weed growth than the correspondent sole crops and greater soil coverage can be obtained by the foliage of the associated systems than by the sole crops. Shading showed considerable potential for reducing the Spread of Cyperus rotundus. Weed growth in maize-groundnut (smother crop) intercrops was less than in the sole crop Of groundnuts (Steiner, 1984). 36 2.7. Influence of Soil Nutrients in the Two Cropping Systems The major soil nutrients for which component crops compete when in limited supply are nitrogen, phosphorus, and potassium. The cereal component, with a faster-growing or more extensive root system, generally has a competitive advantage over the associated legume (Trenbath, 1976). The inability of the legume to compete for these nutrients is attributed to lesser ramification of their root systems (Rabotnov, 1977). Competition for nutrients is impor- tant and could begin early in the growth of the component crops in cereal-legume intercropping systems (Wahua, 1983). Evans (1977) pointed out that the absorption of nitrogen is controlled by the roots of component crops. In cereal-legume intercropping, the legume component is capable of fixing atmospheric N2 under favour- able conditions and this is thought to reduce competition for N with the cereal component (Trenbath, 1976). In the absence of an effective N-fixing system, both cereal and intercrop legume compete for available soil N (0fori and Stern, 1987). In a maize-cowpea intercrop system, Wahua (1983) observed that at 105 kg N/ha, the crops were in competition for N and that this occurred before flowering. Nitrogen uptake by intercrop cowpea was 64 kg/ha compared to 88 kg/ha in the sole crop cowpea. Nitrogen uptake of intercrop maize was reduced by 17 percent compared to sole maize. Without applied N, Chang and Shibles (1985a) and Ofori and Stern (1986) reported strong competition for soil N by intercrop maize and cowpea. This was particularly evident between 49 and 63 days 37 when both crop species were at the reproductive stage and required substantial amounts of N. Intercrop cereal grain yields increased progressively with applied N, while seed yields of companion legumes decreased or were less affected. Phosphorus is a major nutrient that determines, along with other constraints, the production potential of most grain legumes usually intercropped with cereals. Legumes are poorer competitors for P when intercropped with grasses or cereals due to differences in root morphology (Donald, 1963; Jackman and Mouat, 1972; Evans, 1977). Lai and Lawton (1962) evaluated root competition for P between corn and intercrop field bean using 32P labeled fertilizer placed at different depths. They noted that corn was more vigorous in the uptake of P than beans as a result of its more extensive roots. Wahua (1983) observed that maize and cowpea were competing for P and the competition was more evident at flowering. In the absence of applied P, maize was more competitive than cowpea in the initial stages. However, at high rates of applied P, P uptake of intercrop maize was reduced by 30 percent, indicating competition for P from cowpea. Competition was Clearly expressed in the obser- vation that intercrop cowpea took up only 50 percent of the sole cowpea P uptake in the absence of applied P, while at a high level of P, 65 percent was taken up. Remison (1978) concluded that intercropped maize and cowpea grown at two levels of P did not com- pete for P because there was no significant differences in yields of the sole crops and the intercrops. 38 Studies by Drake et al. (1951) showed that cation exchange capacities (CEC) of roots of legumes are approximately double those of cereals. The relatively high CEC of legumes indicates that on soils with low levels of exchangeable K, the legumes would be defi- cient in K because larger amounts of divalent cations would be absorbed by the roots. The level of K in many soils decreases as the growing season progresses. Consequently, K uptake in compe- tition with cereal becomes increasingly difficult for the legume (Drake et al., 1951). Natarajan and Willey (1980b) noted that sorghum was more aggressive for K than pigeon pea, and this severely affected the early growth of pigeon pea. In pigeon pea, K uptake was 28.6 kg/ha in the sole crop and 3 kg/ha in the inter- crop, a reduction of 87.5 percent. Wahua (1983) observed that maize was more competitive for K than cowpea, particularly when N was high. At 50 days after planting, application of 115 kg/ha of N caused reductions of 31 percent in uptake of K in the intercrop maize, and 50 percent in the intercrop cowpea, compared to the respective sole crops. 2.8. Nitrogen Fixation and Transfer by Legume Crop Component In fixing atmospheric N2, legumes contribute to the N content Of soil either as sole crops in rotation or as intercrops (La Rue and Patterson, 1981). In such systems, legumes may either increase the soil N status through fixation and excretion, or in the absence of an effective N-fixation system, compete for N (Trenbath, 1976). 39 The quantity of N2 fixed by the legume component in cereal-legume intercropping depends on the species, morphology, density of legume in the mixture, the type of management, and the competitive abilities of the component crops. Legumes of indeterminate growth are more efficient in terms of N2 fixation than determinate types. Eaglesham et al. (1982) observed that in a growing season soybean fixed more nitrogen than cowpea, but soybean used a greater amount of the N2 fixed to produce seed. Cowpea fixed less N and had a lower seed N harvest index. It thus contributes more N to the soil from its residues. In a sorghum-soybean intercrop system, a tall variety of sorghum reduced soybean yield by 75 percent and N2 fixation at the early pod-fill stage by 99 percent (Wahua and Miller, 1978b). Soybean received more than 90 percent of the incoming radiation with the short sorghum, compared to less than 50 percent with the tall sorghum. Ofori and Stern (1987) noted that cowpea maintained its ability to fix atmospheric N2 when intercropped with maize, but that N2 fixation was reduced by N fertilizer application. Evidence in the literature suggested that the N2 fixed by the intercrop legume may be available to the associated cereal in the current growing season (Agboola and Fayemi, 1972; Remison, 1978; Eaglesham et al., 1981; Pandey and Pendleton, 1986) or as residual N for the benefit of a succeeding cereal crop (Nair et al., 1979; Searle et al., 1981; Singh, 1983). Roots and nodules of legumes are important sources of N transfer because of their high N content 40 (Butler and Bathurst, 1956). Peoples et al. (1983) reported that N from roots and nodules of cowpea were 13 percent of the total plant N. In cowpea, Minchin et al. (1978) noted N from these sources to be only 6 percent of the total plant N. This N quantity may be inadequate to produce any substantial N benefit for a subsequent crop. The degree to which N from an intercrop legume may benefit a cereal crop depends on the quantity and concentration of the legume N, microbial degradation (mineralization) of the legume residues, utilization of these residues, and the amount of N2 fixed by the legume (Henzell and Vallis, 1977; Herridge, 1982). The rate of mineralization of organic N, determined by microbial activity, is primarily influenced by the prevailing moisture and temperature regimes (Ladd and Amato, 1984). Henzell and Vallis (1977) esti- mated that under tropical conditions 30 percent of the N in legume residues could be mineralized and taken up by grass after 24 weeks. The transfer of N was confirmed by the significant dilution of N15 in the intercrop maize compared to sole maize at 25 kg N/ha. They concluded that cowpea and associated maize were competing for applied N and that the N2 fixed by cowpea ended up in the seed and was harvested from the system. These findings were consistent with those reported by Danso et al. (1987) using faba beans and barley. Nitrogen harvested from crops as seed is the largest source of N loss from any cropping system. Assuming N concentration of 1-3 percent in cereal grain and 3-6 percent in legume seed, a 41 cereal yield of 3,000 kg/ha of grain removes 30-90 kg/ha of N from the soil, and 800 kg/ha of legume seed removes 24-48 kg/ha N (0fori and Stern, 1987). Another source of N loss is by volatilization. The important pathways of gaseous N losses from cropping systems are through denitrification, the reduction of N03 to N20 and N2 by microorganisms, and volatilization of NH3. Hauck (1971) concluded that N losses via denitrification could be of the order of 10-30 percent of the N applied, and that this commonly occurs in soils which are wet for prolonged periods. Chalk and Smith (1983) showed that N losses through NH3 volatilization are usually small and that these were generally less than 2 percent of the total N applied. However, on a calcareous soil, Smith and Chalk (1980) measured significant losses of N2 (10 percent) and N20 (6 percent) of applied NH3. Nitrogen losses increased with rising pH. Jewitt (1942) found NH3 losses equiva- lent to 0, 13, and 87 percent of N when ammonium sulfate was applied to soils of pH 7.0, 8.6, and 10.5, respectively. Assuming mean N applied to be 300 kg/ha, the N loss via volatilization was 16.7 percent of N applied from urea, 11.4 percent from ammonium sulfate, and 5 percent from ammonium nitrate. Singh et al. (1978) found in a 180 cm soil profile that maize intercropped with mung bean reduced N03 loss by leaching by 60 percent and by 41 percent when maize was intercropped with blackgram, compared with sole crop maize. 42 2.9. Plant Nutrient Concentration The objective of leaf analysis of crops is to establish critical nutrient concentrations above which no additional yield increase is expected. Tyner (1946) was one of the first to define critical concentrations. He defined it as the concentration above which the response to further fertilization of that nutrient is doubtful. The differences between nutrient uptake by sole-cropped plants and those in the mixture indicate the degree of competition and not necessarily seed yields of each component (Wahua, 1983). Total protein yield was higher for intercrop system over all density combinations (Francis et al., 1982). Average protein content of mature bean seed is 22.3 percent for navy beans (Leveille, 1978). Kelly and Bliss (1975) used four bean strains differing in seed protein quality and quantity with protein content ranging from 21.5 to 31.9 percent. Bean seed nitrogen concentration at physiological maturity was 3.3, 3.21, 3.27, and 3.31 percent N for C-20, Seafarer, Cran-028, and Michigan improved cranberry (MIC), respectively (Mariga, 1987). Bush bean nitrogen content under warm season was 2.62, 2.70, 2.79, and 2.98 percent N for 100, 70, 45, and 27 percent sun, respectively, while 3.28, 2.85, 3.16, and 3.34 percent N were obtained under cool season for the same light regimes, respectively (Eriksen and Whitney, 1984). Seed nitrogen yields under warm season were 71, 90, 77, and 63 kg/ha N for 100, 70, 45, and 27 percent sun while 43 under cool season seed N-yields were 44, 58, 51, 35 kg/ha N for the given light regimes, respectively (Eriksen and Whitney, 1984). Micronutrient concentration for C-20 navy bean at physio- logical maturity was 14.5, 71.8, 27.9, 9.0, and 8.1 ppm Mn, Fe, Zn, Cu, and B, respectively. Seafarer nutrient concentration was 13.9. 63.0, 24.9, 8.5, and 6.8 ppm for Mn, Fe, Zn, Cu, and 8, respec- tively (Mariga, 1987). Micronutrient concentrations for Cran-028 were 11.9, 69.8, 34.1, 10.5, and 10.3 ppm for Mn, Fe, Zn, Cu, and B, respectively, while MIC nutrient concentrations were 11.2, 48.6, 30.1, 10.3, and 9.7 ppm for Mn, Fe, Zn, Cu, and B, respectively (Mariga,'1987). Nutritional content of whole maize grain per 100 grams of edible portion was 9.3 and 73.7 percent for protein and carbo- hydrates, respectively, while kidney bean protein and carbohydrates were 21.7 and 60.9 percent respectively (FAO, 1968). Mmbaga (1980) obtained 25-27 percent protein in San Fernando bean while maize hybrid 5802 in association with San Fernando produced 7.7 to 9.6 percent protein at East Lansing, Michigan. Maize grain protein concentrations (N x 6.25) ranged from 6 to 10 percent depending on fertility levels (Rendig and Broadbent, 1979). The nitrogen con- centrations in both sole and intercropped maize in the two experi- ments were similar. Hence, the larger seed nitrogen yields of the sole maize compared with those of the intercrop maize were due to differences in grain yield, and indicative of competition between maize and cowpea for nitrogen when intercropped (0fori and Stern, 44 1987; Wahua, 1983). Nitrogen yield of maize grain increased significantly with each rise in maize density (0fori and Stern, 1987). Grain percent N of maize in monoculture was 1.2 while maize in association with cowpea had 1.1 percent N. Nitrogen yield (kg N ha'l) was 107 and 63 for sole and mixed cropping, respec- tively (0fori and Stern, 1987). Beauchamp et al. (1976), using selected inbred lines of maize, obtained grain percent N values ranging from 1.90 to 2.10 percent in 1970, while in 1971 the same inbred lines had grain percent N ranging from 1.37 to 1.81 percent. Tyner (1946) and Dumenil (1961) Observed a significant relationship between maize yield and N, P, and K concentrations in the ear leaf. Maize and cowpea compete for N, P, K, and Ca. The competition stress showed up clearly around the time of anthesis for each crop; 50 DAP for maize and 40 DAP for cowpea. Maize nutrient accumulation for crops grown in monoculture did not differ appreciably from those of plants in the mixture with cowpea (Wahua, 1983). Nutrient uptake (kg ha‘l) of maize was 185, 3.97, 176, and 157 for N, P, K, and Ca, respectively, in monoculture. Maize in association with cowpea had nutrient uptake of 163, 3.89, 156, and 142 kg ha"1 for N, P, K, and Ca, respectively (Wahua, 1983). Average elemental composition of maize ear leaf in a monocultural system was 3.39, 0.31, 2.15, 0.59, and 0.30 percent for N, P, K, Ca, and Mg, respectively (Dahl et al., 1982). Maize ear leaf micronutrient concentration was 40, 45 65, 13, 3, and 150 ppm for Zn, Mn, Cu, B, and Fe, respectively (Dahl et al., 1982). CHAPTER 3 MATERIALS AND METHODS Two cultivars of beans, Domino (upright, small, black seeded, indeterminate type II with short vines) and Carioca (climbing, small, brown and tan speckled seed, indeterminate type III) (Singh, 1982), were evaluated at three densities in association with maize hybrid 422 (a short season cultivar) on the Michigan State Univer- sity Agronomy Farm at East Lansing, Michigan. Treatment combina- tions included monocultural maize, Domino, and Carioca; and Domino in association with maize at 10, 15, and 20 bean plants/m2 (equiva- lent to 100,000, 150,000, and 200,000 plants/ha, respectively). Carioca was also grown in association with maize at 10, 15, and 20 plants/m2. A total of nine treatment combinations were tested in 1984, 1985, and 1986, representing first, second, and third growing seasons, respectively. The experiment was planted in a randomized complete block design with four replications on a Capac fine loamy soil (mixed mesic, Hapludolfs) 0-3 percent slope. Bean rows in monoculture were 4 m long, 0.5 m wide, and 0.1 m Spacing within the row, representing 20 plants/m2 (200,000 plants/ha). A 3 m long section of the central four rows of the eleven row plot was harvested for seed yield, leaving a 0.5 m border on each end of the four rows (6 m2). The fifth central row was used for sampling dry matter. Five bean rows grown in association with six maize rows were 4 m long, 1 m wide, and 0.1, 46 47 0.07, and 0.05 m Spacing within the row, representing 10, 15, and 20 plants/m2, respectively. A 3 m long section of the central two rows of beans in association with maize was harvested for seed yield, leaving one bean row on each side of the plot and 0.5 m from each end of the two central rows as border rows (6 m2). Dry matter data of bean in associated culture was sampled from the third central row. Monocultural and associated culture rows of maize were 4 m long, 1 m wide, and 0.5 m spacing within the row (two plants/hill), representing 4 plants/m2 (40,000 plants/ha). These maize rows planted in association with beans were 0.5 m distant from the bean rows. Three central rows of maize (consisting of seven plant hills each) were harvested for grain yield while the fourth central row was sampled for leaf nutrient concentration of maize, leaving one row of maize on each side of the plot and one plant hill at each end of the three central rows as guard rows (10.5 m2). Fertilizer application rates of 30, 45, 45 kg/ha NPK, respectively, were applied at planting to both crop species. Maize plots received an additional 120 kg N/ha as a top dress application when maize was 0.6 m high. A mixture of metolachlor (2.3 kg a.i./ha) and chloramben (2.3 kg a.i/ha) herbicides was applied and incorporated before planting as recommended practice for maize-bean mixtures. Several traits were observed, measured, and recorded during the course of the experimental period. A caliper was used to measure stem diameter of the five plants sampled during 48 physiological maturity. Plant height, effective pods/m2, seeds/ pod, and nodes/plant were recorded at physiological maturity. Hundred seed weight and seed yield were measured and recorded at harvesting. Biomass yield was recorded at mid-pod filling and total biomass was measured at harvesting to calculate harvest index (HI). Bean dry weight, total non-structural carbohydrate (TNC), mineral nutrient concentration, light penetration, and leaf area were also Observed and recorded as detailed below. 3.1. Dry Weight Five competitive bean plants (uniform competition) were uprooted in each plot biweekly starting at 50 percent flowering and continuing to physiological maturity. Fifty percent flowering was the time when 50 percent of the plants had at least one open flower. Physiological maturity referred to the stage when not less than 95 percent of the pods turned from green to tan, yellow, or brown colour and the plant had reached maximum dry matter accumula- tion. Each plot sample was partitioned into roots, stems and petioles, leaves and pods (pods only at mid-pod filling and at physiological maturity). The samples were dried in an oven at 80°C for 72 hours. Dry weights were recorded and plant tissues were ground in a standard motor driven Wiley laboratory mill to pass through a 40 mm mesh screen. Ground samples were stored in plastic storage bags (zip-loc type) for determination of starch. 49 3.2. Total Non-Structural Carbohydrate (TNC) Analysis Oven-dried bean root, stem, and leaf tissues sampled from plants at mid-pod filling in 1984, 1985, and 1986 were analyzed for sugar and starch concentrations. Duplicates of 100 mg samples were placed in 100 ml beakers. A blank sample was included for every 24 samples. About 30 ml of 80 percent ethanol was added to each beaker for sugar extraction. Beakers were heated in a steam bath for one hour and then left to cool for about 20 minutes. The ethanol solution was poured through Whatman No. 2 filter paper into a 125 ml Ehrlenmeyer flask. The filtrate volume was raised to the 100 ml mark with distilled water and mixed well by shaking. The residue was washed from the filter paper into the appropriate beakers and evaporated in a 60°C oven until dry. Beakers containing tissue residue were cooled and kept in an ice bath throughout the starch extraction procedure. For each beaker, 10 ml of cold (0°C) 30 percent perchloric acid was added to a beaker containing the dry residue. A glass rod was used to stir until a paste was formed. Beakers were mixed by swirling every 5 minutes for 40 minutes. Samples were filtered through Whatman No. 2 filter paper into a 125 ml Ehrlenmeyer flask. Beakers were rinsed and filtered into appropriate flasks. The volume in each flask was raised to the 100 ml mark by adding distilled water and mixed well by shaking. Glucose (from Sigma 510-A kit) was used to make working standard solutions from 0-100 mg/L for bean sugar analysis 50 (Appendix L). The stock standard concentration was 1,000 mg/L glucose. A set of glucose standards was prepared for each rack of 24 samples. Cornstarch was used to make the starch standard solu- tions from 0-100 mg/L for bean starch analysis (Appendix M). The starch stock standard was prepared by weighing 1 g of cornstarch and adding 1 ml ethanol (95 percent) plus 100 ml sodium acetate buffer (0.1 M, pH 4.2). The mixture of cornstarch, ethanol, and sodium acetate buffer was heated on a hot plate just to boiling. The mixture was cooled in a water bath and transferred to a 200 ml volumetric flask. Sodium acetate buffer was added to bring the final volume to 200 ml. The stock standard contained 5,000 mg/L starch (0.5 percent starch). Volume Of stock standards was dispensed accordingly into clean, labeled test tubes and distilled water was added to bring the volume to 4 ml. I One ml of sugar and starch sample and 1 ml of glucose and starch standards each were pipetted into a test tube and 1 ml of 5 percent phenol solution was added to each tube and then mixed by vortexing. Five ml of concentrated (96 percent) H2504 were quickly added to produce mixing and uniform heat distribution. The test tubes were vortexed and left to stand for 10 minutes. The test tubes were vortexed again before being placed into a water bath (ZS-30°C) for 20 minutes for colour development and stability. Absorbance of glucose and starch standards and sample solu- tions were read at 490 um absorbance using a Lambda 4B UV/VIS spec- trophotometer C688-0001. The absorbances of the standards were 51 plotted against their known concentrations by using the NCSS programme. The standard curves were linear and the regression equation and correlation values were obtained (Appendix N). Bean carbohydrate concentrations were Obtained by multiplying the absorbance of bean sample by the regression equation values (Y = .1485 + 100.9877 x ABS) to Obtain mg/L sample. Percent sugar or starch concentration of bean was obtained by the following equation: Percent sugar/starch concentration of bean _ 1.0 g x 100 ml final volume mgLL sample ' 0.1 g 1.0 ml x 10,000 mg sample sample (10,000 mg = 1%) weight solution Sugar and starch concentrations were converted to gm/kg by multi- plying percent sugar/starch by 10 (1% = 10 gm/kg). Total non- structural carbohydrate (TNC) was obtained by adding sugar and starch concentrations. 3.3. Mineral Nutrient Concentration Determination of the total spectrum of mineral nutrient con- centration was conducted for leaves and seeds of bean and maize. Young, fully expanded bean leaves were picked from a 3 m long section of the central two or four rows of each plot (one tri- lfoliate leaf from each plant) for associated and monocultural plots, respectively, at first flowering, making a total of thirty leaves per plot. Likewise, a total of fifteen maize leaves were 52 sampled just above the ear from each plot at tasselling for the determination of mineral nutrients. These samples were dried for 72 hours to a constant weight in an oven at 80°C. Leaves and seeds of maize and beans were ground in a standard motor driven Wiley laboratory mill to pass a 40 mm mesh sieve and were stored in plastic storage bags (zip-loc type) for the determination Of total mineral nutrients. Five hundred milligrams of ground samples from each plot were weighed on an analytical balance and were placed in Clean numbered crucibles and were covered immediately. The crucibles were dry- ashed in a muffle furnace for five hours at 500°C. The furnace was preheated for one hour to stabilize at 500°C. Samples were left to cool and 25 ml of digestion solution (3N HN03 in 1000 ppm LiCl 12.22 gm LiCl + 375 ml Nitric acid and volume was raised to 2 litres by adding distilled H20) were added to each crucible and were left for one hour for the digestion to be completed. The solution was filtered into labeled vials which were then capped with linerless caps. Mineral nutrient concentrations of both crop species were determined by the use of a D.C. plasma emission spectrophotometer. High and low standards were included as checks for every 20 samples. For the determination of nitrogen (protein), 250 mg of ground seed and leaf samples were weighed on an analytical balance and were placed in Kjeldahl digestion flasks. Three ml of concentrated H2504 and one Kjeldahl tablet (catalyst--a 100:10:1 mixture of 53 K2504, CuSO4 - 5H20, and Selenium, were added to each flask. The flasks were set on the block digestor. The micro Kjeldahl pro- cedure (Bremner and Mulvaney, 1982) was used to digest samples for three hours or until colourless at 375°C. After digestion, samples were cooled for 20 minutes and diluted to 100 ml volume with dis- tilled water and representative amount of digested solution was poured into labeled vials (20 ml) and covered. Total seed and leaf N of bean and maize was determined by the quickchem system auto- mated ion analyzer (Lachat). Percent protein of bean and maize in each plot was obtained by multiplying percent N by 6.25. 3.4. Light Penetration and Leaf Area Light penetration was estimated by using the ozalid paper technique of Friend (1961). Ten sheets of ozalid paper were stapled together and then cut into booklets of 2 x 2 cm. The booklets were placed in black-painted petri dishes with the light sensitive side facing the sun. The booklets were attached to the cover by plastic tape. Light reached the booklet through a 0.5 cm diameter unpainted window on the cover. The petri dishes were sealed with plastic tape to protect the booklets from weather damage. The petri dishes were placed at the top and bottom of bean canopy in each plot in the two-cropping systems between 7 and 8 pm and were collected after 24 hours. The exposed booklets were placed in wire baskets and the baskets were suspended in an air-tight plastic container containing concentrated ammonium hydroxide. The booklets were suspended in 54 the air-tight plastic container for at least three hours. A count of the number of bleached papers gave an estimate of the amount of light penetration in each plot. To convert the number of papers bleached to percent relative light interception, ozalid papers were exposed for varying lengths of time to direct sunlight and calcula- tions were based on direct sunlight. Light intensity was directly measured with a light meter (Lambda Instruments model LI-188 with a quantum sensor). Leaves sampled for dry matter weight at mid-pod filling were also used for measuring the leaf area. Five trifoliate leaves were picked alternately from the main stem of each of the five plants and their areas and weights were measured and recorded. Leaf area was measured with a portable leaf area meter (Lambda Instruments model LI-300). The leaves were dried and leaf area index was determined by: 2 . Leaf Area Index (LAI) = Leaf area/m ) x Total Dry Weight (gm) Specific Dry Weight (gm)x m2 of Ground Area In order to isolate interactions, the Michigan State University Stat 4 package (factor factorial) was used for analysis Of variance for all the traits during the experimental period. CHAPTER 4 RESULTS 4.1. Bean Performance in the Two Cropping Systems Analyses of variance for bean yields and yield-related traits in associated culture are shown in Appendix A, Tables A1-A3. Effect of seasons was highly significant for biomass, plant height, pods/m2, stem thickness, leaf area index, hundred seed weight, seed yield, relative light interception, nodes per plant, bean seed protein, nitrogen, phosphorus, and potassium yield (Appendix A, Tables A1-A3). Biomass, pods/m2, bean seed phosphorus yield, and seed yield in associated culture for the 1984 growing season were significantly higher than in the 1986 cropping season (except one treatment; Table 1). Furthermore, leaf area index in the first growing season was significantly larger than the leaf size Obtained in the second season. Highly significant cultivar differences were observed in plant height, pods/m2, stem diameter, hundred seed weight, seeds per pod, and bean seed potassium yield (Appendix A, Tables A1-A3). Significant (p < 0.05) cultivar differences were also observed for nodes per plant and seed yield in associated culture (Appendix A, Tables A1-A3). Domino had significantly more seeds per pod generally than Carioca. However, the hundred seed weight of Carioca was significantly greater than for Domino. Bean seed yield, bean seed protein, phosphorus and potassium yields, pods/m2, 55 56 ._m>w_ mo.o we“ we gmsuo some see; pcmgmyewc apucmo_ewcmwm Ho: wee Amvcmuum_ maem ms» :u_z mcmnszz "muoz m.o~ ARV >8 mH Amo.ov ems mu mm mm mm mm mm :mmz ass—cu onMM Comm. uan mime «mm mumww mama Asov mcmm mmov muom meow meow mom mmmfi ugm_m: ammm tome coca comm mmm apex «mmH asap; 0.“ Aev >0 m.H Amo.ov ems NH NA mH NH ma ma cum: :Eapou nomw uumw onmw umw. uamw uuwfl emmfi oamH _ UUNH nova nmvfi nmea mma vwmfi ucm_a\mmuoz w.m ARV >8 8o.o Amo.ov ems ¢.o m.o «.0 m.o m.o o.o com: cszpou vwdm owdm nmqm qum ownm. omqm ommfi Aguv u¢.o u¢.o uv.o um.o n¢.o no.o mmmfi gmumsm_o om.o um.o um.o no.0 um.o m~.o ewmfi swam muo_gmu o:_soa moowcmu o:_soa muowcmu o:_Eoo me> u_mcp com omH ooH Ae;\_a mofiv mm_awmcma :mmm umaqogocmpcm .mczupau emumwuomm< one cw muwmcp team—mmiupm_> ucm ume> comm co x¢_m:mo cmmm new .Lm>FD—:u comm .cmm> mo uumeem .H m_amp 57 cacao socw acmcmwm_u Amo.o v av x_u=eu>>>:m>m m_ mo.o mg» on cmguo :umm Eocw “cmngCPu apucmo>w>:m_m Ho: wee Amvcmuam_ Arv xm_cmumm cm zu_: cmxcma cmm> maem we» ;u_z msmnE=z .mcmm» ._m>m_ "muoz e.m ARV >u m.o Amo.ov am; e e o > m > :88: eE>_eu 8m em, em am am 8M ewm> no e> no e> no e> emm> eoe\memmm o.>N >>v >8 mm Amo.o> ems NHH Nm> mOH em> om moH e88: ee5>oo ;-Cmmu 8-8mww 5-8mm: 5-8MMT comm. swan 8mm> m-um>> 88o>> m-e>m eeomfl ;-L>> C-u>oH mmm> Beoe> neo>> BUQM> momfl cemNH eaoefi emm> ~e\muoe >.em A>V >8 >N mw mm >N NN mm :88: =E>_ou mm mm mm mm mm mm 8mm> ARV eo_eaeu om mm mm mm om ON ImamH -LmeeH u;m_> mm mm mm on mm mm emm> e>_ee_eg moo_cmo ocwsoo euo_>mo o:_soo muo_cmo o:_soo me> “Page com om> 00> >8;\_e moHv mm_g_mcmo comm umanocucmacfi .A.e.eeoov H m_ne> 58 ._m>m> mo.o we» we cmeuo seem seem ucmcmmw_u a_u:eu>w>:m>m Do: men Amvcmuump maem me» new: memeE=z ”muoz N.e> Aes >e see Ame.es ems >ee eme e>> mee ee> e>> eeez e2e_ee 8-8eee e-e>Ne e-emmm e-eeee emee emmm ewes Aee\ess emmee L-U~Ne emeee e-eeee emmme e-e~m> mees e_e_> moses eeeess e-e~ee enmess e-e>ee> e-emmm «ems eeem e.em Aes >e Ne Ame.es ems ees ees ems mes see ems ewe: eEe_ee PMMI wummmw _TQMMfl _;mm1 Psmm1 Pgwml ommfl e-8ee> e-ees~ e-eems e-em>> _eee _-Lses meme A~e\es mmom unnamm unmmm aefiwm mnnofim unmmm ewmfi mmmsowm e.es Aes >e m.e Ame.es ems m.~ e.~ e.N e.N e.s e.s eeez ege>ee uuoflqw ciaMdM wicwdw miumdw unamdm mivmdm mwmfi eee.s e-mm.s e-em.> eee.s eee.> em.s meme xeeee em.m uee.~ uem.~ ee.~ e-ee.~ e-em.~ eee> maze ewes euoweeo ocwsoa euo_ceu ocpeoo eoomgeu o=_soo Lem> “Page eeN eme ees Aee\_e meme mm>u_m=mo cemm umeeoguemuee .A.e.eeees s B>ee> 59 mo.o ms“ we Loewe seem soc; ucmcmwmwu appcmu_w_emwm no: ._m>mp wee Amvcmuum_ maem we“ zu_3 mcmnazz "muoz N.ee Aes >0 mm Amo.os ems emN ~>N Nee emu eemz eEe_ee cumMM onmww vmmw nmmw mama emee eeeme es>s eemse meme Aee\exs emsm eesm ee>m~ eesmm ewes emeeeee m.m Aes >e N Ame.es ems mm em mm es em ms :88: ee=_ee mwM 3mm «WM 3mm mww an mama AEav eeN Des eeN ems emu Bee mees Deemme eeem Gee See new ems emm ems eees emceeee , e.e Aes >e m Ame.es ems mm mm em mm em mm eeez eEe_ee uiemw miumw uremw uiemm. uuemw comm ommfl Aev xmuem mmm miumm unnmm muwm uiemm mmm emma umm>gez euo_ceu o=_soo euo_ceu ocmsoo eoo_ceu o:_soo cem> emcee eeN eee Am;\—a moHv mm_u>m=ma :emm cmeeoeuemucm .>.e.seees e m>ee> 6O .mcemx emeuo soc; pcmgmGCPu Amo.o v as a_geeuww_cm_m m_ ARV xmmemume ce gum: cmxeee eem> .—m>m_ mo.o mew pm emzpo some soc; ucmgmwe_u x—uceu_w>:m_m no: use Amvcmpump msem we“ euwz memeszz "muoz e.ms Aes >e N Ame.es ems es ms e ss eemz,eEe>ee mumw coda GMT mm! .ommH em ems we ness mees see\ess ems ems gems ems ewes se>mmesee e.>s see >e s sme.es ems e m m e new: :Ez—ou um um. mm om mama 8e em em 8e mees see\ess we em em em eees meeeeemeee e.es see >e em me em mm eeez ee3>ee mm mm NM. mm ewes em e8 em em mees see\ess em em Ne ee seems emeeeemz euo_ceo oemsoo euowceo o:_soo muo_gmu ocwsoo Lem» u_ech eeN ems ees Aee\_e mess mm_u_m=mo comm vmeeocugmch .>.e.eeees s m>ee> 61 and biomass increased with bean density but not significantly so in some treatments (Table 1). Bean roots, stems, leaves, and pod dry weight generally increased with increasing bean density. Maximum stem and leaf dry weight was achieved at around mid-pod filling and declined toward physiological maturity (Table 2 and Figures 1 and 2). However, root dry weight did not peak at any physiological stage. Root dry weight within each density remained similar throughout the three physiological stages (Table 2 and Figure 3). Bean density levels significantly (p < 0.01) increased stem diameter and seed yield (Appendix A, Tables A1-A3). Domino (100,000 plants/ha), during the first season, had significantly larger stem diameter than for the last two seasons. Seed yield of Carioca at 200,000 plants/ha in the first season was significantly higher than for the last two seasons. Similarly, density increased biomass and leaf area index of Carioca, and reduced nodes per plant of Domino significantly (p < 0.05) in the first season (Table 1). Domino, at 200,000 plants/ha, had significantly fewer nodes per plant than at a lower plant density in the 1984 cropping season. On the other hand, Carioca had a significant increase in leaf area index and biomass when it was planted at 200,000 plants/ha than when it was planted at lower bean densities during the first season. A significant year x cultivar interaction (p<:0.05) was Observed for plant height, harvest index, bean seed protein, phos- phorus, and potassium yield (Appendix A, Tables A1-A3). A similar 62 Table 2. Effect of Bean Density on Dry Weight of Bean Cultivars in the Two Cropping Patterns. Three Year Average Dry Weight (gm/m2) Density First Mid-Pod Physiological (103 pl/ha) Trait Flowering Filling Maturity Intercropped 100 Domino 7d-f 6e-9 7d-f 150 Roots BC'e 8C'e 3c-e 200 gb-d gb-d gb-d Monoculture 200 19a 20a 19a Intercropped 100 Carioca 49h 49h 3h 150 Roots 49h 49h 49h 200 5f-h 5f-h 5f-h Monoculture 200 10bC 11b 9b-d LSD (0.05) 2.3 CV 22% Intercropped 100 Domino 37f 426f 33f 150 Stem 44ef 47ef 44ef 200 soef 49ef 48ef Monoculture 200 9ocd 119a IOObc Intercropped 100 Carioca 35f 39ef 35f 150 Stem 39ef 47ef 4Oef 200 46ef 56e 4zef Monoculture 200 80d 115ab 109ab LSD (0.05) 17.7 CV 30% Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 63 Table 2 (cont'd.). Three Year Average Dry Weight (gm/m2) Density First Mid-Pod Physiological (103 pl/ha) Trait Flowering Filling Maturity Intercropped 100 Domino 46d-f 45d-f 35f 150 Leaves 530-e 53c-e 45d-f 200 58cd 55cd 54c-e Monoculture zoo 107b 125a 105b Intercropped 100 Carioca 43d-f 44d-f 39ef 150 Leaves SIC-e 546-e 45d-f 200 58cd 64c 48d-f Monoculture 200 110ab 125a 1133b LSD (0.05) 15.4 CV 25% Intercropped 100 Domino asef 109C-f 150 Pods 73d-f 132b-d 200 77d-f 147bc Monoculture 200 176b 356a Intercropped 100 Carioca 45f 1OBC-f 150 Pods 58f 125b-e 200 53f 125b-e Monoculture 200 150bc 388a LSD (0.05) 65 CV 34% Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 64 mmmeum m>>pu=coeemm acmgmw$_o we :emm mo u;m_m3 xgo swam .fi mgemme >s_eeoaz .eomeo_o_m>ee eee-e_z Lose—e ems . A sew site ee ee> IIIIII... .1. r .. e: E 8qu «I. (Isl .1. (Ibo. 090.com i . m m I i 1.1.x l .1 m. $358022... r....--- ............... - IIIIIIIIIJIJII $1111...» l (1.5 8.32 e? . e r . 1|, m BE eeeemm RAHIITTJ: Till). .. «IE 1. ee ee... (11...... Tailuflllililll, . Ilrilfllllul . - 1.1—”.th r III...” .I x5111. IAwm was: .89....8... Tillllrllllkxtx. . outmog PDOIJPQ 65 mammum m>_uu=uocamm acmemew_o um comm we ugmwm: age Gems .N mc=m_e xu_eauez pmu_mo—o_ma;e cce-u_z szo_m umH .. Alma ee..e.e> (1.1.... S 4.1.x. ha Goodmr TIIIIIrIIIIIIIIIf A T .1st 0853 T Jillluri - m - . Tswm Isum $55 200202 r........... 1-...-. - JIlIIJIIIfIIIIleILlIIlu-IIILII IT ON 5 x . - .wn anew waxes .. IT 4 a .... . .. . ll 1. site eee eee FITMTIIJIIIIIYI . e Tgwm was: 8020: «1111...... TIT....I......1...I8 Home (aw/ms) (aw/46) 9301483 outmog 66 momeum m>_pu=uocemm ucmcmww_o we game we u;m_w3 ego Doom .m me=m_e memeeoez _ao_ee_e_m>ee eoe-emz Loze_e ems 11') IIIEIE+JIE a be 869 illili ...........I......._. a: .E Sebfi a .l .. a:....>a coo nee r 1.. 1.. C? ,— TITTIIrrITTIITTT [5": P mess>ssseso>ee2 Tllllllllrflllllilll... em. 0 al....HE 88.8. Ti... 1.... - «it 08.8. .4 II t 1... . . site enemas... s A. 1. .T r mm_.;s.suo_.._m__ss Fill... - IIIIIIIIIIIIrIII IIIIIII‘ I... p.._ —. (zm/wfi) 6 (aw/w ) 9301483 outmoa 67 year x cultivar interaction was noted for hundred seed weight, seed yield, and nodes per plant at the 1 percent probability level. Carioca plant height in the 1984 growing season (first growing season) was significantly (p < 0.05) taller than its height in the second growing season. Domino vine length was significantly shorter than Carioca in all growing seasons (Table 1). Bean cultivar performance in the first season was significantly higher in seed yield, bean seed phosphorus, and potassium yield as compared with observed performances in the third growing season. Hundred seed weight of Carioca in the second season was signifi- cantly lower than its weight in the first and third cropping seasons. Carioca's seed protein yield in the first season was significantly higher than any corresponding value in the second and third seasons (Table 1). A significant year x cultivar x density interaction was observed for biomass, stem thickness, leaf area index, and nodes per plant at the 5 percent probability level (Appendix A, Tables A1-A2). Carioca planted at 200,000 plants/ha had a signifi- cantly higher biomass in the first season over its biomass and Domino's biomass in the second and third cropping seasons (Table 1). Similarly, the leaf area index of Carioca (200,000 plants/ha) in 1984 was significantly larger than its leaf area index in the second and third growing seasons (Table 1). Domino's leaf area index (LAI) for the entire experimental period was sig- nificantly smaller than Carioca LAI at 200,000 plants/ha in the 68 1984 cropping season. Domino had significantly more nodes per plant at 100,000 plants/ha in 1984 than it had and Carioca had in the 1986 growing season. The stem thickness of Domino in 1984 at 100,000 plants/ha was significantly larger than its stem thickness and the stem thickness of Carioca obtained during the entire experimental period (Table 1). Results of beans planted simul- taneously with maize indicated non-significant year x density and cultivar x density interactions for bean yield and yield-related traits (Appendix A, Tables A1-A3). Bean traits measured under monoculture compared with traits measured under associated culture Showed that the monocultural seed yield, biomass, relative light interception, pods/m2, leaf area index, bean seed protein, nitrogen, phosphorus and potassium yields, bean roots, stems, leaves, and pod dry weights of each cultivar ‘were significantly (p < 0.05) greater (Tables 2 and 3). The stem thickness of Domino under monoculture was either not sig- nificant or Significantly thicker than the stem thickness of Domino grown in association with maize. Stem thickness of Carioca under monoculture was not significantly different from stem thickness in association for the first and second growing seasons. However, the stem thickness of Carioca under monoculture in the 1986 cropping season was significantly thicker than Carioca's stem thickness in associated culture. 69 me.e mes oe Loeso eooo coco seocoommo x—ucou_mpcm_m poc mco Amvcmuum— msom mcu cum: mcmnszz .—m>mp "muoz e.mm Ame >e e.em sme.es ems mm mm mm mm mm mm mm mm com: csapou miuMM nimww cuwMI. xicmm nomw xucmw unmm w-mmw mama Asuv cummm x-_oe cummm xi_o¢ ciwom xiwmm :Twom swam mama unmwm: unomm wiumm oooH wicmo owm muoem omm mimem «mad acopm e.e Ame >e m.s sme.es ems NH NH mm NH mm mm em «a com: csz—ou comw comw ueMfl uww mama comw nomw coma mmma can“ coma coca coca poem oma coca omH emmfi “co—m\mmuoz >.m Ams >e o.e sme.es ems ¢.o m.o «.0 m.o m.o m.o m.o N.o comz cs:_ou owed owmm omnm omnm ommm ommm emnm. omnm emes Aces u¢.o c¢.o c¢.o um.o ue.o em.o we.o am.o mmma cmumso_m um.o um.o om.o am.o um.o om.o mm.o ou.o cmmfi Empm ouomcou ocwsom ouowcou ocwsom ooowcou oc_som ouowcou ocpEom com» u_ocp ocm om“ oc\_a ooo.oo~ ucoum comm mpom mm_o_mcmm comm omeeococmucm Aoc\—a moHv :_. mumeh flmumpumltpmw> Ucm U_.m_.> :cmm co huwmcma :mmm Dem .Lm>_.u_.:u cmmm .me> we HUQHCM .mccmuuoe mc_eeocm ozh mg“ .m o_eoo 7O mo.o mcp no cmcuo cuom Eocm ucmcmmVPc a—ucooPEPcm_m mo: mco Amvcmpum— maom mcu cum: mcmnE:z .—m>m> "muoz s.m Ame >e m.e sme.es ems m m m N m N m N com: casmom am am am oM om oM oM oM mama am on no oN am on om on emmfi noe\mummm >.NN sms >e om sme.es ems NHH NmH moH emH om mom emu mom com: csapoo n-mmwl wnwmwfi mummMI wimMMI nPMMI wwml madam. ummM mama wimmfia muonfi muwmm m-mom~ nicnm w-meoH comH uokm mmma m-uoe~ mcoufi mimomH coma c-mmm~ w-uo¢H oomm noomm cmma Ns\mcom m.>~ Ame >e e.Ns Ame.es ems em mm mm mm mm mm mm mm com: cszpom uan uan uawm. unNM. onww umM omw omm mama Amy co_uqmu mom unmm onmm onmw mom mom omm omm mmmfi -Lmucm acmws nmm nmm nmm onom unmm nmm omm oom qwmfi m>wuopmm ouowcom oc_som ooo_coo oc_som ooowcou oc_som ouowcou ocwsom com> p_och com omfi ooH oc\Pq ooo.oom Aae\_e mees mm_a_mcmm comm cmecocucmucm ccopm comm m_om .A.o.oeeov m o_eo> 71 ._m>m_ mo.o 93 um gmsuo comm 50.; HcmLmHEFU hpucmuw$wcmwm Ho: 9; Amvgwuum— $.53 93 3.2.3 ”man—=32 ”muoz e.m> Ame >e eem sme.em ems eem emm o>> mee me> e>> eeem emee coo: eEe_oe s-eeee s-e>me s-_mmm s-_eee smeo semmm eeeme eemee emem soe\ess semee _-mN~e smeee e-eeem semme s- Nee oo>mmm omemm mmem o>om> moosmm o-oNNsm e-a~me m-o-sm e-o>eem e-omme ommem omemm emem ooom e.mm see >e eem Ame.es ems med emm eom mmm smm emm >>m mee eooz eE>_ee :MNI cimwmfl cmmww :wml cmwl cWWI unnwmw unwww mmmfi e-oeee e-oeme e-oems e-om>> ewe e-esem o-e~e~ eemm mmem Ame\es oeeem o-oeNN o-omNN o-eHmN e-oe>~ m-e~m~ oeee e>me emem mmoEeme m.s~ Ame >e >.e Ame.es ems m.~ e.~ e.~ e.~ e.H m.> e.m m.m eooz eE>>oe cIuMdM minMdM wummdw wiumdm snuMUM wiwmqw uunde nfldm ommfi wc¢.H _-mm.a Pimm.H Pcv.H wce.H _m.H Pimm.m $-um.m mmmH xmncm oem.m m-oe.~ o-om.~ o-oe.~ e-o~.~ m-om.~ om.e a~.e emee ooze Coos ouowcou oc_som ooomcou ocwaom ouo_com ocmeom ouomcou ocmsom com> “mock eeN eme eem oe\_e eee.ee~ Ao;\_q moHV mm_u_mcmm comm umaaocucmucm ucoum comm m_om .A.o.oeeov m o_eo> 72 me.e oeo oo Loeoo eooo coco oeocommmo x—ucoo_m_cm_m uoc moo Amvcmuum_ msom mco cum: mcmaE=z .—m>m_ ”muoz m.m> mes >e N> Ame.es ems mmm mmm NHN mHN mom Nmm com: csapom c-meM mimmmm stm ctwmmw nmmw ammm mmmfi eeme> oammm emes e-om>N o>mm oeme memm soe\ess mcmmm mccmm mcemm m-mmmm ommm osmm ommH cmmoocm m.m mes >e e.m Ame.es ems mm mm mm mm cm mm mm mm comz csepom omw comm oww comm oWM. comm omm comm mmmH AEmv coom mmH comm mmm onmm mmH nmm mmH mmmH ocmwmz cmmm ocm mmH ocm mm“ omm mmH ocm mcmH cmmm cmccccx s.e Ams >e e.m Ame.em ems mm mm mm mm em mm cm om com: cs:_ou wion mimwm wiomw ciomw miomw miomw comm onmm cmmH ARV xmccH comm m-mmm m-cmm mwcm w-o~m mmm omm comm cmm~ umm>coz ooomcou oc_som ooo_cou oc_som ooo_com oc_Eom ooo_com ocpsom com> opoce com oc\_c coo.oom mmmommcmm comm cmeeococmocm soe\>e meme ccoom comm mpom .A.c.oeeos m m_eo> 73 mo.o mco mo cmcoo coom seem ocmcmmm_c myocoommmcmmm ooc mco Amvcmoom_ ._m>m_ msom mco cow: mcmeazz ”mooz e.em mes >e >.m sme.es ems NH mm m Hm em Nm eaoz eE>>oe _-mmfl cmww PM! _gml nmw cam mmmfi mee e-omm _em ee>e oNH oHN memo Aoe\ess ocem moms e-cN> e-om> wee oee emmo semmmooee m.em Ams >e m.s sme.es ems e m m o >> >> eeoz eEe_ee firm _:m cm n_m cwl owfl mmmH ch :mm nwm wcc mmm mcm mmmH Aoc\mxv moo eem eem eem mes emm eemm meeeeemeea e.ms Ame >e >.Hm sme.es ems me me em mm mem eem eooz eEe>ee cummm. mimwm cMM comm nmdm. nwmfl mmmH eeeN e-oee eNN eeem on oeN mmme Aee\ess ooem ooem o-o>e e-oee oemm oemm eeem eoeeoomz ooopcoo oc_som ooowcom ocpsom ooomcou oc_som com» umoce eeN oe\_e eee.eeN soe\>e mems mm_o_mcmm comm cmeeococmocm ccoum comm mpom .A.c.ocoov m m_eo> 74 4.2. Bean Carbohydrate Concentration Year effects were significant for all carbohydrate traits except leaf starch concentration (Appendix A, Table A4). Root and stem starch, sugar, and TNC concentrations were significantly higher in the second growing season than in the first and third cropping seasons (with a few exceptions; Table 4). 0n the other hand, leaf sugar and TNC concentrations were significantly reduced in the first season as compared to the second season (except a few treatments), possibly due to increased sink capacity in the first year. Differential effects of cultivars on bean root sugar, stem starch, sugar and stem TNC, and leaf starch, sugar, and TNC concentrations were not significant (Appendix A, Table A4). A significant density effect occurred for root starch, sugar, TNC, stem starch (p < 0.01), stem TNC, leaf sugar, and leaf TNC (p < 0.05) concentrations (Appendix A, Table A4). Year x density interactions in bean carbohydrate concentration were not Signifi- cant. However, CUltivar x density interaction was significantly expressed in root sugar, stem starch, TNC (p < 0.01), root TNC, and stem sugar (p < 0.05) concentrations (Appendix A, Table A4). Furthermore, significant year x cultivar x density interactions were observed for root sugar, TNC, and stem starch (p < 0.01) concentrations (Appendix A, Table A4). Carioca (200,000 plants/ha) root sugar and TNC and stem starch concentrations in the second growing season were significantly higher than all the corresponding values in the first and third seasons (Table 4). 75 Table 4. Effect of Year, Bean Cultivar, and Bean Density on Bean Carbohydrate Concentration during Mid-Pod Filling in the Associated Culture. Associated Culture (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Root 1984 33cd 3Id 426d 36cd Starch 1985 726 31d 776 57b (gm/kg) 1986 §§cd §§cd 35c égcd Column Mean 48 32 54 43 LSD (0.05) 12 CV (1) 19.7 Root 1984 456-6 41de 47cd 466d Sugar 1985 626b 456-e 54bc 716 (gm/kg) 1986 ggfg 259 ééef glfg Column Mean 46 37 46 49 LSD (0.05) 10 CV (%) 14.2 Root TNC 1984 79bc 73b-d 89b 82bc (gm/kg) 1985 1346 76b-d 1316 1286 1935 _§§cd QQd _§ch _§ZCd Column Mean 94 70 100 92 LSD (0.05) 17 CV (%) 13.4 Stem 1984 416-6 35de 35de 48bc Starch 1985 55b 45b-d 51bc 826 (gm/kg) 1935 géde 29c 'fllc-e ééde Column Mean 44 37 42 55 LSD (0.05) 12 CV (%) 18.8 Stem 1984 72bc 626d sod 79bc Sugar 1985 1086 1066 1056 1166 (gm/kg) 1986 _7_4bc .mb fl“ .811bc Column Mean 85 78 79 92 LSD (0.05) 20 CV (%) 16.4 Note: Numbers with the same ferent from each other at the 0.05 level. letter(s) are not significantly dif- 76 Table 4 (cont'd.). Associated Culture (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Stem TNC 1984 113de 97ef 86f 127cd (gm/kg) 1985 164b 151bc 156b 1986 1986 119°‘f _2§°f 121° lléde Column Mean 129 115 122 147 LSD (0.05) 25 CV (B) 13.7 Leaf 1984 22 25 26 24 Starch 1985 23 26 25 24 (gm/k9) 1986 31 29 25 29 Column Mean 23 26 25 25 CV (%) 12.7 Leaf 1984* 25 25 29 31 Sugar 1985 40 37 35 43 (gm/k9) 1986 29 32. £9 £1 Column Mean 34 31 35 38 CV (B) 17.4 Leaf TNC 1984* 47 50 55 55 (gm/kg) 1985 63 63 60 67 1986 99 §§ 95 91 Column Mean 57 57 60 63 CV (B) 10.5 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 77 A year x cultivar interaction was observed for root starch (p < 0.01), root TNC, and stem starch (p < 0.05) concentrations (Appendix A, Table A4). Carioca, at 200,000 plants/ha, had sig- nificantly higher stem starch concentration in the second growing season than the Domino and Carioca stem starch concentrations in the first and third growing seasons (Table 4). Root starch con- centration in Domino in the second season was significantly higher than in Carioca during the same season and Domino and Carioca values in the first and third seasons. Similarly, the root TNC concentration for Domino during the second growing season was sig- nificantly higher than for Carioca and Domino in the first and third cropping seasons and for Carioca (100,000 plants/ha) in the second season. A comparison of the cropping patterns indicated that the two systems did not differ significantly with respect to their effects on leaf carbohydrate concentrations (Table 5). No distinct trend was observed between the two cropping systems in regard to root and stem carbohydrate concentrations. Root starch concentration in Domino, in maize-bean association, at both densities during the second cropping season was significantly higher than in all other combinations except monocultural Domino (Table 5). Root sugar con- centration of Carioca (200,000 plants/ha) during the second growing season was similar to monocultural Domino root sugar concentration but was significantly higher than any treatment combination in the two cropping patterns (Table 5). 78 Table 5. Effect of Year, Bean Cultivar, and Bean Density on Bean Carbohydrate Concentration during Mid-Pod Filling in the Two Cropping Patterns. Sole Bean Stand Associated Culture (103 pl/ha) 200,000 pl/ha 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Root 1984 51bc 42cd 33d 31d 42cd 36d Starch 1985 826 sobc 726 31d 776 57b (gm/kg) 1986 Aflb-d ézcd §§cd §§d fish-d gfid Column Mean 59 43 48 32 54 43 LSD (0.05) 14 CV (B) 21.2 Root 1984 szd-f 52d-f 456-9 419h 476-9 466-9 Sugar 1985 6369 59P-d 6269 45f-h 54C:e 71?. (gm/kg) 1935 §§h1 2213 2913 394 gghl glij Column Mean 50 47 46 37 46 49 LSD (0.05) 9 CV (B) 13.7 Root TNC 1984 Iozcd 946-6 796-9 73f-h 89d-f 826-9 (gm/kg) 1985 1466 109c 1346b 76f-h 1316b 128b 1986 _89_e-9 .699" .689" 99“ .8169 £19" Column Mean 109 90 94 70 100 92 L50 (0.05) 17 CV (%) 13 Stem 1984 46b-f 40d-9 416-9 35f9 356-9 48b-e Starch 1985 726 54bc 55b 45b-f 51b‘d 826 (gm/kg) 1986 596-9 §§f9 366-9 ggg 41C'9 gge-g Column Mean 53 43 44 37 42 55 LSD (0.05) 13 CV (B) 20 Stem 1984 67d-f 9Obc 726-e ozef 50f 796-6 Sugar 1985 1136 1136 1086b 1066b 1056b 1166 Column Mean 84 94 85 78 79 92 LSD (0.05) 20 CV (%) 16.8 Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Note: Table 5 (cont'd.). 79 Sole Bean Stand Associated Culture (103 pl/ha) 200,000 pl/ha 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Stem TNC 1984 113f9 130d-f 113f-h 979h 86h 127ef (gm/kg) 1985 1856b 167bc 164bc 1516-e 156cd 1986 1986 1409” Mfg .11_0f-h 3.6.9“ 2161' 1&9 Column Mean 136 137 129 115 122 147 LSD (0 05) 27 CV (%) 14.5 Leaf 1984 27 27 22 25 26 24 Starch 1985 25 24 23 26 25 24 (gm/k9) 1986 25 22 21 29 £5 29 Column Mean 26 25 23 26 25 25 CV (B) 11.9 Leaf 1984 32 31 25 25 29 31 Sugar 1985 39 35 4O 37 35 43 (gm/k9) 1986 21 33 29 22 £9 11 Column Mean 34 33 34 31 35 38 CV (B) 16.1 Leaf TNC 1984 59 59 47 50 55 55 (gm/kg) 1985 64 60 63 63 60 67 1986 59 §§ 99 §§ .95 £2 Column Mean 60 59 57 57 60 63 CV (B) 10.4 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 80 Root TNC concentration of Domino under monoculture was not significantly different from its root TNC value in associated culture at both densities in the second season but was Signifi- cantly higher than the other treatment combinations (Table 5). The two associated density levels did not generally differ markedly in root total non-structural carbohydrates within each growing season (Table 5). Stem starch in Carioca at the higher density during the second year was Significantly higher than the corresponding values in the two cropping patterns except stem starch concentration of Domino under monoculture (Table 5). Stem sugar concentration for both cultivars under monoculture was not Significantly different from their stem sugar concentration in associated culture during the 1985 season. However, stem sugar concentration in the second season was Significantly higher than the stem sugar values of the remaining seasons (Table 5). Stem TNC of Carioca at the high density during the second year was not Significantly different from Domino stem TNC concentration under monoculture. However, it was significantly higher than the rest of the treatment combinations in the two cropping patterns (Table 5). The two levels of density combinations did not differ significantly (with few exceptions) in stem TNC within each growing season (Table 5). 81 4.3. Bean Mineral Nutrients 4.3.1. Bean Seed Mineral Nutrient Concentration The analyses of variance for seed nutrient concentrations of bean in association with maize are presented in Appendix A, Table A5. Cultivars differed significantly (p < 0.05) for boron and potassium concentrations (Appendix A, Table A5). 0nly boron showed a significant (p < 0.05) year x cultivar interaction (Appendix A, Table A5). Boron concentration in Carioca was Significantly higher than Domino's boron values during the first season. However, Domino's potassium concentration was signifi- cantly higher than the Carioca potassium values in the third season (Table 6). Significant cultivar differences were also observed for iron and copper concentrations at the 1 percent probability level. Iron concentration of Domino was significantly higher than in Carioca in 1984. Similarly, copper concentration of Domino was significantly higher than Carioca copper concentration in 1986. The results in Appendix A, Table A5 indicated that the effect of density on seed nutrient content was not significant. No signifi- cant year x density, cultivar x density, and year x cultivar x density interactions were observed for bean seed nutrient concentration. A comparison of seed nutrient contents in monoculture with those contents in associated culture indicated that protein, nitrogen, phosphorus, magnesium, boron, molybdenum, and zinc concentrations did not vary Significantly (Table 7). However, 82 Table 6. Effect of Year, Bean Cultivar, and Bean Density on Seed Nutrient Concentration of Bean in the Associated Culture. Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Protein 1984 260 280 280 260 (gm/kg) 1985 280 260 280 .280 1986 m 289 3.09 2E Column Mean 283 273 287 270 CV (%) 9 Nitrogen ' 1984 42 45 45 41 (gm/kg) 1985 45 42 44 45 1986 19 L4 9.6 :8 Column Mean 45 44 46 43 CV (%) 9 Phosphorus 1984* 5 4 5 5 (gm/kg) 1985 5 5 5 6 1986 § 1 5 4 Column Mean 5 4 5 5 CV (%) 12.2 Potassium 1984 146 12c 13b 13b (gm/kg) 1985 14a 14a 14a 14a 1935 13a lgc 13a 19b Column Mean 14 13 14 13 LSD (0.05) 1 CV (%) 6.5 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 83 Table 6 (cont'd.). Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Calcium 1984 2 2 2 1 (gm/kg) 1985* 1 2 2 2 1986 1 1 .1. .1. Column Mean 1 2 2 1 CV (%) 16.1 Magnesium 1984 2 2 2 2 (gm/kg) 1985 2 2 2 2 1986 2 2 2 2 Column Mean 2 2 2 2 CV (%) 5.7 Boron 1984 10¢ 11b 10¢ 11b . (mg/kg) 1985 10¢ 10¢ 9d 9d 1986 lib lib lib lga Column Mean 10 11 10 11 LSD (0.05) 1 CV (%) 7.3 Copper 1984 12b¢ 11¢d Izbc 12b¢ (mg/kg) 1985 146 12b¢ 146 136b 1986 lied _§e 19d _§e Column Mean 12 10 12 11 LSD (0.05) 2 CV (%) 13.8 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 84 Table 6 (cont'd.). Bean Density (103 pl/ha) r 100 200 Trait Year Domino Carioca Domino Carioca Iron 1984 806 71¢d 796b 70¢d (mg/kg) 1985 71¢d 64d 68¢d 69¢d 1935 Ingc §§cd Zia-c §§cd Column Mean 74 68 74 69 LSD (0.05) 8 CV (%) 8.0 Molybdenum 1984* 6 5 6 6 (mg/kg) 1985 4 4 4 4 1986 3 3 1 5 Column Mean 4 4 5 5 CV (%) 19.1 Manganese 1984* 13 12 . 13 13 (mg/kg) 1985 10 10 10 10 1986 _1_4 1_3 e 1_2 Column Mean 12 '12 12 12 CV (%) 9.1 Zinc 1984 34 35 34 37 (mg/kg) 1985 32 36 32 40 1986 a 3.3. 2 25. Column Mean 33 35 33 37 CV (%) 13.8 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p .< 0.05) different from other years. 85 Table 7. Effect of Year, Bean Cultivar, and Bean Density on Seed Nutrient Concentration of Bean in the Two Cropping Patterns. Sole Bean Stand Bean Density (103 pl/ha) 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Protein 1984 270 270 260 280 280 260 (gm/kg) 1985 280 270 280 260 280 280 1986 299 2.6.9 3.19 $9 399 2.79 Column Mean 277 267 283 273 287 270 CV (%) 8.9 Nitrogen 1984 42 43 42 45 45 41 (gm/kg) 1985 45 43 45 42 44 45 1986 91. 4_2 99 9 4_8 4_4 Column Mean 44 43 45 44 46 43 CV (%) 8.9 Phosphorus 1984 5 5 5 4 5 5 (gm/kg) 1985 5 6 5 5 5 6 1986 5 fl 9 fl 9 2 Column Mean 5 5 5 4 5 5 CV (%) 11.3 Potassium 1984 13b 13b 146 12¢ 13b 13b (gm/kg) 1985 146 13b 146 I46 146 146 1935 lib lgc lfla lac 13a lib Column Mean 13 13 14 13 14 13 LSD (0.05) 1 CV (%) 5.9 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Table 7 (cont'd.). 86 Sole Bean Stand Bean Density (103 pl/ha) 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Calcium 1984 1b 1b 26 26 26 1b (gm/kg) 1985 26 26 1b 26 26 26 1935 ga _ga lb lb lb .lb Column Mean 2 2 1 2 2 1 LSD (0.05) 0.4 CV (%) 15.4 Magnesium 1984 2 2 2 2 2 2 (gm/kg) 1985 2 2 2 2 2 2 1986 2 2 2 2 2 2 Column Mean 2 2 2 2 2 2 CV (%) 5.9 Boron 1984 10 11 10 11 10 11 (mg/kg) 1985 10 9 10 10 9 9 1986 m 1_0 1_1 1_1 U 1_2 Column Mean 10 10 10 11 10 11 CV (%) 7.9 Copper 1984 11b-d 10¢-e 126-¢ Ilb-d 126-¢ 126-¢ (mg/kg) 1985 136b 126-¢ 146 126-¢ 146 136b 1935 123‘9 _§e 119'“ _§e ch-e _§e Column Mean 12 10 12 10 12 11 LSD (0.05) 2.5 CV (%) 15.5 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 87 Table 7 (cont'd.). Sole Bean Stand Bean Density (103 pl/ha) 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Iron 1984 736b 63b-6 806 716b 796 706-¢ (mg/kg) 1985 516 57¢-6 71ab 54b-e 53a-d 69a-c 1935 zgab §§de Zgab éga-d Zflab ééa'd Column Mean 66 58 74 68 74 69 LSD (0.05) 13.8 CV (%) 14.3 Molybdenum 1984 5 4 6 5 6 6 (mg/kg) 1985 4 4 4 4 4 4 1986 9 fl 9 9 fl 9 Column Mean 4 4 4 4 5 5 CV (%) 17.8 Manganese 1984 12bc 12bc 136b 12b¢ 136b 136b (mg/kg) 1985 10d6 96 10d6 10d6 1096 10d6 1935 12bc llCd 13a lgab 13ab 12bc Column Mean 11 11 12 12 12 12 LSD (0.05) 1.3 CV (%) 8 Zinc 1984 32 32 34 35 34 37 (mg/kg) 1985 34 34 32 36 32 40 1986 29 2.8. 9 2 2 a Column Mean 34 31 33 35 33 37 CV (%) 13.3 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 88 mixed results were obtained in each season for potassium, calcium, copper, iron, and manganese concentrations (Table 7). Copper, Fe, and Mn concentrations of the two cultivars in monoculture were not significantly different from their corresponding concentrations in associated culture in each season (with few exceptions). Potassium concentration of Domino in association with maize (except one treatment) for the three seasons was Similar to Domino's under monoculture and Carioca's potassium values under associated culture in the second season but was significantly higher (with one exception) than all the remaining values. 4.3.2. Bean Leaf Mineral Nutrient Concentration Bean leaf nutrient concentration results in associated culture are presented in Appendix A, Table A6. Seasonal effect was highly significant (p < 0.01) for phosphorus, potassium, calcium, magnesium, boron, copper, molybdenum, manganese, and zinc concen- trations. Calcium and manganese concentrations were Significantly lower in 1985 than their corresponding concentrations in 1984 and 1986. Magnesium concentration, on the other hand, was signifi- cantly higher while copper concentration was significantly lower in the first season than in the last two seasons. Significant seasonal effect was also observed for protein and nitrogen concen- tration at the 5 percent probability level (Appendix A, Table A6). 0n the other hand, cultivar effect on phosphorus and potassium concentration was significant at the 5 percent probability level and boron, molybdenum, and zinc at the 1 percent probability level 89 (Appendix A, Table A6). Phosphorus and potassium concentrations of Carioca (100,000 plants/ha) were significantly higher in the second season while its Zn concentration was Significantly higher in the first season than Domino's values within the same season (Table 8). A significant (p < 0.05) year x cultivar interaction was observed for boron concentration while the year x cultivar inter- action was highly Significant for protein, nitrogen, and molybdenum concentration (Appendix A, Table A6). Protein and N concentrations in Carioca were Significantly increased in 1985 over corresponding Domino's trait values during the same season. Similarly, B and Mo concentrations of Carioca were Significantly higher in 1986 than Domino concentrations within the same season. Effect of bean density on bean leaf nutrients was not significant. Similarly, year x density interaction was not significant for the bean leaf nutrient concentration. Furthermore, no Significant effect was observed for cultivar x density or year x cultivar x density interactions in bean leaf nutrient levels (Appendix A, Table A6). A comparison of bean‘ leaf nutrient concentrations under monoculture with the leaf nutrient concentrations of bean in associated culture is presented in Table 9. Leaf protein, nitro- gen, phosphorus, potassium, calcium, magnesium, and copper of bean under monoculture were not Significantly different from their leaf nutrient concentrations of bean in associated culture (Table 9). Bean leaf boron concentrations of the two cropping patterns did not differ Significantly in the 1984 and 1985 growing seasons. 9O Table 8. Leaf Nutrient Concentration of Bean as Affected by Year, Bean Cultivar, and Bean Density in the Associated Culture. Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Protein 1984 27O¢-6 2906-d 27O¢-6 290b-d (gm/kg) 1985 2406 3206b 250d6 3106-¢ 1986 3906 M16 £96 2.196-c Column Mean 283 290 287 303 LSD (0.05) 50 CV (%) 12.3 Nitrogen 1984 43b-d 476-¢ 44b-d 476-¢ (gm/kg) 1985 39d 526 40¢ 506b 1986 549 flgcd 549 Egab Column Mean 45 47 46 49 L50 (0.05) 8 CV (%) 12.3 Phosphorus 1984 4C 4c 4C 4c (gm/kg) 1985 5b 66 5b 5b 1986 5b Qa .Qa 9a Column Mean 5 5 5 5 LSD (0.05) 0.9 CV (%) 12.5 Potassium 1984 17¢d 17¢d 16d 17¢d (gm/kg) 1985 24b 316 21b-d 23b¢ 1986 glb-d glob ggb-d géab Column Mean 21 25 20 22 LSD (0.05) 7 CV (%) 21.4 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 91 Table 8 (cont'd.). Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Calcium 1984* 35 39 33 38 (gm/kg) 1985 19 20 19 19 1986 3.8 4_o 29 m Column Mean 31 33 29 32 CV (%) 26.4 Magnesium 1984* 13 13 13 12 (gm/kg) 1985 6 7 7 7 1986 _8 .9 _9 .19 Column Mean 9 10 10 10 CV (%) 9.9 Boron 1984 36¢ 38¢ 35¢ 37¢ (mg/kg) 1985 37¢ 41c 37¢ 38¢ 1935 §§b Ego {ézb gga Column Mean 44 49 43 48 L50 (0.05) 8 CV (%) 12.2 Copper 1984* 10 11 10 11 (mg/kg) 1985 19 20 17 16 1986 1.7 m 17. 1_7 Column Mean 15 16 15 15 CV (%) 21.2 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 92 Table 8 (cont'd.). Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Iron 1984 502 699 581 580 (mg/kg) 1985 366 368 343 359 1986 3.19 99 1% 991 Column Mean 396 557 450 502 CV (%) 19.5 Molybdenum 1984 11b 11b 11b 11b (mg/kg) 1985 7d 7d 7d 7d 1986 19C lga 19c lib Column Mean 9 10 9 10 LSD (0.05) 1 CV (%) 8.1 Manganese 1984* 126 161 94 126 (mg/kg) 1985 29 33 31 30 1986 1_10 1_19. 91.7. 1.1.3 Column Mean 88 104 77 90 CV (%) 27.3 Zinc 1984 39f 536-¢ 4Of 4sd-f (mg/kg) 1985 426f 48b-6 40f 426f 1986 Ego-f §§ab gla-d §§a Column Mean 42 52 44 48 LSD (0.05) 8 CV (%) 12.4 Note: Numbers with the same letter(s) are not Significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 93 Table 9. Leaf Nutrient Concentration of Bean as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns. Bean Density (103 pl/ha) Sole Bean Stand 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Protein 1984 310 280 270 290 270 290 (gm/kg) 1985 240 280 240 320 250 310 1986 999 919 949 299 390 .39 Column Mean 300 290 283 290 287 303 CV (%) 11.8 Nitrogen 1984 50 45 43 47 44 47 (gm/kg) 1985 39 44 39 52 40 50 1986 5_7 99 99 9 9.4. 9 Column Mean 49 46 45 47 46 49 CV (%) 11.8 Phosphorus 1984 4 5 4 4 4 4 (gm/kg) 1985 5 5 5 6 5 5 1986 9 9 9 9 9 9 Column Mean 5 5 5 5 5 5 CV (%) 12.2 Potassium 1984 17 17 17 17 16 17 (gm/kg) 1985 23 23 24 31 21 23 1986 a a a a .22 m Column Mean 20 21 21 25 20 22 CV (%) 21.3 94 Table 9 (cont'd.). Bean Density (103 pl/ha) Sole Bean Stand 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Calcium 1984 36 40 35 39 33 38 (gm/kg) 1985 19 18 19 20 19 19 1986 9 99 .39 99 99 4_0 Column Mean 30 34 31 33 29 32 CV (%) 24.7 Magnesium 1984 12 13 13 13 13 12 (gm/kg) 1985 7 7 6 7 7 7 1986 .19 1_0 .9 .9 .9 19 Column Mean 10 10 9 10 10 10 CV (%) 10.2 Boron 1984 35d 39d 36d 38d 35d 37d (mg/kg) 1985 35d 35d 37d 419 379 38d 1986 égc .§lbc §§b §§a ézbc éga Column Mean 40 42 44 49 43 48 LSD (0.05) 7 CV (%) 11.3 Copper 1984 14 13 10 11 10 11 (mg/kg) 1985 16 17 19 20 17 16 1986 14. 1_4 1_7 .19 1_7 1.7. Column Mean 15 15 15 16 15 15 CV (%) 22.9 Note: Numbers with the same letter(s) are not Significantly dif- ferent from each other at the 0.05 level. Table 9 (cont'd.). 95 Sole Bean Stand Bean Density (103 pl/ha) 200 100 200 Trait Year Domino Carioca Domino Carioca Domino Carioca Iron 1984 486¢-6 7286 502Cd 6996b 581b¢ 580b¢ (mg/kg) 1985 3976-9 381d-9 3666-9 3686-9 343fh 359f9 1986 29“ 214.8" 919‘"-h fl“ fid'f 97.6 Column Mean 371 461 396 557 450 502 LSD (0.05) 123 CV (B) 19.1 Molybdenum 1984 11b 11b 11b 11b 11b 11b (mg/kg) 1985 76 76 76 76 76 76 1935 _gd lib 19¢ 19a 19C lib Column Mean 9 10 9 10 9 10 L50 (0.05) 1 CV (B) 8.1 Manganese 1984 127b 122b¢ 126b 1616 94¢d 126b (mg/kg) 1985 286 296 296 336 316 306 1986 1196-9 £9 1_wb¢ 9996 11966 mm Column Mean 85 73 88 104 77 90 LSD (0.05) 31 CV (%) 25.2 ”Zinc 1984 42d-f 596 396f 536-¢ 406f 45¢-6 (mg/kg) 1985 42d-f 45¢-6 42d-f 489-6 406f 42d-f 1935 éga-c flgb-e flgb-e §§ab gla-d §§a Column Mean 45 51 42 52 44 48 LSD (0.05) 9 CV (%) 13.2 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 96 However, bean leaf boron of Carioca grown in association with maize was Significantly (p < 0.05) higher than the monocultural values in the 1986 growing season. Bean leaf boron concentration of Domino grown in association with maize was either significantly (p < 0.05) higher or remained similar to the monocultural boron concentration in the 1986 growing season (Table 9). Similarly, leaf zinc concentration of Domino grown in associated culture did not vary significantly from its monocultural value within each growing season. Zinc in Carioca under monoculture was either not significant or significantly higher than zinc concentration in associated culture (Table 9). Leaf manganese of Domino in monoculture was not significantly different from leaf manganese concentration in associated culture for the 1985 and 1986 growing seasons. 0n the contrary, Domino leaf manganese planted at 200,000 plants/ha was significantly lower than leaf manganese concentration in Domino in monoculture in the 1984 cropping season. Leaf manganese of Carioca in monoculture was either significantly (p < 0.05) lower or not significantly dif- ferent from leaf manganese of Carioca in associated culture for the 1984 and 1986 cropping seasons (Table 9). Bean cultivars grown with maize had Similar molybdenum concentrations as their monocultural counterparts for the 1984 and 1985 growing seasons. However, the concentration of molybdenum in monoculture for the 1986 cropping season was either not significant or significantly lower than the molybdenum concentration in the 97 intercropping system (Table 9). Leaf iron concentration of Domino in monoculture was not Significantly different from the concentra- tion of iron in the associated culture for the 1984 and 1985 cropping seasons. 0n the contrary, leaf iron concentration of Carioca in monoculture was Significantly (p < 0.05) higher than iron concentration of Carioca (200,000 plants/ha) grown in associa- tion with maize during the 1984 cropping season. Leaf iron concentration of Carioca in the 1986 season was significantly higher in the intercropped system than in monoculture (Table 9). 4.4. Maize Performance in the Two Cropping_§ystems Results of maize yield and yield-related traits in asso- ciation with bean cultivars are presented in Appendix A, Tables A7 and A8. Effect of bean cultivars on maize traits was not signifi- cant. No year x cultivar interactions were observed in maize traits except grain potassium yield, which differed Significantly at the 5 percent probability level (Appendix A, Tables A7 and A8). Maize grain potassium yield was significantly higher during the third growing season than any other season when maize was grown in association with Domino (Table 10). Significant bean density (p < 0.01), year x density (p < 0.05), and year x cultivar x density (p < 0.05) interactions were observed only for maize plant height (Appendix A, Tables A7 and A8). Plant height of maize intercropped with Carioca (100,000 plants/ha) was significantly Shorter in the 1985 growing season than the maize-Domino association within the same season and bean 98 .mcom» cmcoo some ucmcmmc_c Amo.o v av apocoomcmcmmm m_ «V xmmcmomo co cum: cmxcos com» ._m>m— mo.o mco uo cmcoo coom some ucmcmmomc apocoomc_c mm ooc moo Amvcmoump msom mco co_3 mcmcszz "mooz m.mH Ams >e em em Ne me eeoz eEe>oe mms. Nam MMN mmm .eeem seeNess eN me Ne em meem o_e_> mm mm mm me omem eoeecomz m.mm Ame >e Nee eem eeo Hem eooz eEe_ee mmm. mmm. mmm mmM .eeem see\ess eee ‘ Nmm Noe mNm moms o_em> Nmm eem mem Nee eeem e_oooee N.N Ame >e N sme.es ems sem eNH eee mom oem em” :66: eEe_oe cicmmw cmmw cowmw comma ommM nommm mmmfi AEoV omem omem ommm Como cmes eeem meem eeemoe commH comma comma c-noom c-o~om o-omo~ cmmfl mNFoz oooPLom ocNEom ooowcom ocmsom ooomcom oc_Eom com> o_ocp- eeN emm eee mee\>e ems msmmeoe eeoe seems oe eococe em see\>e eee.ees oomez .mcaopau cmoomoomm< mco e_ meeee> oooe_oe-c_om> oeo c_om> onmoz :6 >emmeoe eooe oeo .co>me>eo eooe .coo> me ooeoom .ee o_eo> 99 cmcuo Eocw ocmcmmc_c Amo.o v av mpucoo_m_cm_m m_ mo.o mco oo cmcoo coom soc» ocmcmccPc x_ocoowc>c M .mcom» «v smmcmomo co com: cmxcoe com» .Pm>m> _m we: mco Amvcmoom_ msom mco co_: memeszz ”mooz N.N sms >e Nm Hm Nm me No mm eooz eEe>ee mm mm _Mm mm Mm mm eeem Aces semeoz Nm Hm Nm em Nm Nm mmem oeom mm mm mm mm mm em eme> cocoeee e.m Amy >e m sme.es ems mm mm mm mm com: cszpou onmm amm cam owm mmmfi Aoc\mxv eeN ecmN eeeN eNmN memm o_o_> comm mccm mcmm wmmm emmH sawmmouom e.mm Ame >e mm mm em Nm eooz eEe_ee mm mm mm. mm emem Aoe\ess mN NN mN NN emeeH o_om> mm mm mm Nm eeem meceeemeee ooomcom oc_aom ooowcou oc_Eom oooPLom oc_som com> o_oce eeN eem oAV xo_mcmm comm neo_z co eecoca em Aee\_e eee.ees meme: .>.c.eeeom es e>eoe .mcom» cmcoo seem ocmcmmmmc Amo.o v as a_ocoo_m_cmwm m_ Ass xm_cmomo co co_z cmxcos com» ”mooz 100 o.e Aes >o meem eeem eeme mNeo eNee eemm eeoz eEe>ee meee mHeN emNN mNeN meme NmeN .emem Aoe\ess o_o_> emee emmm emem emom NNee HeNm meme emece mNem meom memm Hmem eNem emmm eeem meme: e.> Ame >e mN.H eN.H eN.s eN.e NN.H eN.> eooz eEe_ee eN.m MN.> HN.H >H.s mN.H eN.s emem Aemss o_ooe mm.s mm.e mN.H Nm.> >N.> NN.H mee> eeo_e>_eee em.m eN.> mN.H eN.H HN.H e>.> eeme oeos ooo_cou oc_som ooowcou oc_som ooomcou oc_som com> o_ocp eeN emm ees woe\_e mess mommeoe eeoe Neomz co eeeoceeem Aoe\_e eee.eos meme: .>.o.seeos em o_ee> 101 density level. Significant (p < 0.01) seasonal effect was observed on maize plant height, maize grain yield, grain protein, nitrogen, phosphorus, and potassium yield (Appendix A, Tables A7 and A8). Grain yield, grain protein, and nitrogen yield of maize in asso- ciated culture in the 1986 cropping season was higher than in 1984 and 1985. Maize associated with beans during the 1985 growing season yielded less grain phosphorus and potassium than the 1984 and 1986 yield for these elements. A comparison of monoculture with the associated culture maize performance is shown in Table 11. Hundred seed weight of maize in monoculture was not Significantly different from that of the inter- crop weight. Maize in sole crop stand was significantly taller than maize in associated culture during the 1985 growing season. Maize grain protein and nitrogen yield differences in associated culture in 1984 and 1986 were not significant with the exception of the maize-Domino combination at 200,000 plants/ha which yielded Significantly lower than the monocultural maize (Table 11). Furthermore, protein and nitrogen yields of maize under monoculture in the 1985 growing season were significantly higher than the counterpart in associated culture at the 5 percent probability level. Similarly, grain phosphorus and potassium yields of maize in monoculture in 1985 were significantly (p < 0.05) higher than grain phosphorus and potassium yields of maize in association with beans (Table 11). ._m>m_ mo.o mco oo cmcoo coom soc» acmcmmmmc apocoo_m_cmmm ooc moo Amvcmuomp msom mco co_3 mcmnszz ”mooz e.ms sms >e m.e> Ame.es ems mm cm em mm NHH comz caspou comma cmww eomww nowmw ommw mmmm Aoc\mxv ome omm omm ocm nofiwa mmmm c—mm> omm omm omm omu omm ommm cmmocuwz e.m> Ame >e e.>es sme.es ems Nmm omm com Hmm ace com: csapou nommm nmmm comwm nomwM ommm mmmfi Aoc\mxv ocmc ommm oNHm ommm commm mmma c—m_> oemm oocm omom ommo omom cmmm cwmooce a. e.N sms >o m.N Ame.es ems w Hma m2 3: mmfi mmH omH mm“ com: cs: :5 oiommM ommfl owmw onmww ommM nommw ommm mama AEoV mmcm mmcm cmmmm momma mmom momH coma mmmm ucmwm: oemmH oemH onH o-ooo~ o-omom o-omo~ o-oHom cmmm m~_oz ooowcom ocwEom ooo_cou oc_Eom oooPLou ocwsom Aoc\_a ooo.ocv com» owoce oeoem memo: 6.6m com omH ooH MoeN>e ems mommeoe eooe Neo_z co eecocemec Aoe\_e eee.ees oN_oz .mccmuooc mc_ceocu ozh mco c_ mo_oce cmoopmm-c_m_> cco c—m_> m~_oz co »o_mcmm comm cco .co>mo_=m comm .com> co oommmm .HH mpeo» 103 ._m>m_ mo.o mco uo cmcoo coom Eocc ocmcmmc_c xpucoo_w_cmwm uoc mco Amvcmoomp mEom mcu co_z mcmnscz ”mooz m.> Ame >e mm Hm mm mm mm Hm cm comz cs:_ou mm mm Mm mm mm mm mm emem Aces see_oz mm Hm mm cm mm mm cm mmmfi cmmm Hm mm Hm mm mm mm mm ommH cmccczm m.m Amy >0 ¢.m Amo.ov mms mm em mm mm mm comz ce:_om 6-6mm o-omm o-ewm ewm. 6mm memo Aee\ess now n-cm~ HAN w_mm o-omm mmmH cpm_> m-mmm c-om~ c-mem _-mmm m-oom ommfi E:_mmoooe o.e> Ame >e e.e sme.es ems Hm Hm Hm mm mm com: cszpou ciawm mioflm onmm oiomm oiomm. mmma Aoc\mxv mmw mmem mmm ccem ooc mmmH c_mm> eoem eeem o-emm o-eNm oem emem meceeemoee ooo_com oc_Eom ooo_cou ocwsom ooo_cou ocwsom Aoc\_e ooo.ocv com» o_oce ccoom mNNoz mpom com omH ooH Mee\>e ems mommeoe eeoe seem; co eococo ee soe\_e eee.ees meme: .A.c.oeoos Hm o>ee> 104 .Pm>m~ no.0 mco oo cmcoo coom Eocc ucmcmcm_c apocoommwcmwm ooc mco Amvcmoum_ mEom mcu cow: mcmaszz "mooz m.e Ame >e NmN sme.es ems meem emem eeme mNee mNee emmm oeeN eoaz eEe_ee eomeeN emmeN eommNN emNeN eommeN eoneN emsmN omem see\e¥s c>om> eemee o-oemmm oomeem e-oe>em ooNNee oomeNm emHsN mmem emece _ oomeem oomeem comemm cosmem e-oeNem o-oemmm omeem emmm BNNoz N.e Ame >e Hm.e sme.es ems mN.e mN.H eN.H eN.H NN.H eN.> ee.m eeoz eEe>ee o-emN.m o-emN.H o-omN.H o>>.H o-emN.s ooeN.m oee.m eee> Aeess emsoe ems.m omm.m o-oeN.H eeNm.s e-oHN.m e-eNN.m oee.> meem oeo>o>meem o-omm.s o-oeN.H o-emN.H o-eeN.H o-oHN.H ooem.m oee.> eees oees ooo_cou oc_Eom ooowcom ocwsom ooowcom ocmsom Aoc\_c ooo.ocv com» prose oeeem eomez o_om com omH ooH Mee\_e ess >ommeoe eeoe Neemz co eecocomem soe\>e eee.ees ammo: .A.c.ucoov HH m—noh 105 On the other hand, phosphorus and potassium yields of maize in monoculture were either not Significant or significantly higher than maize yield in associated culture for the 1984 and 1986 growing seasons. Land equivalent ratio (LER), which ranged between 1.15 and 1.35 in associated culture, was significantly higher than the LER under monoculture throughout the experimental period. Grain yield of maize in monoculture in the 1984 cropping season was not significantly different from that of the associated culture maize (Table 11). However, the grain yield of maize in sole crop stand in 1985 significantly out-yielded the corresponding yield value in associated culture at the 5 percent probability level. Other observations indicated that maize in association with Domino at 150,000 and 200,000 plants/ha yielded Significantly lower grain than the grain yields of maize under monoculture during the 1986 cropping season (Table 11). 4.5. Maize Mineral Nutrient Concentration 4.5.1. Maize Grain Mineral Nutrient Concentration Results of grain nutrient concentration of maize in associa- tion with bean cultivars are shown in Appendix A, Table A9. Bean density significantly (p < 0.05) affected grain copper concentra- tion of maize. Grain copper concentration of maize was generally lower when maize was intercropped with beans at 200,000 plants/ha than when it was associated with 100,000 bean plants per hectare (Table 12). Furthermore, grain copper concentration of maize in association with Domino (100,000 plants/ha) was significantly 106 Table 12. Grain Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Associated Culture. Intercropped Maize (40,000 pl/ha) with: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Protein 1984* 90 90 100 90 (gm/kg) 1985 100 100 100 100 1986 99 99 99 19 Column Mean 97 97 100 97 CV (%) 7.4 Nitrogen 1984* 15 15 15 15 (gm/kg) 1985 16 16 16 17 1986 9 1.7 9 9 Column Mean 16 16 16 16 CV (%) 7 4 Phosphorus 1984 6 6 6 6 (gm/kg) 1985 5 5 5 5 1986* 9 9 9 9 Column Mean 5 5 5 5 CV (%) 7.6 Potassium 1984 5a 5a 5a 5a (gm/kg) 1985 4b 4b 4b 4b 1986 §a 3b ‘éa 5b Column Mean 5 4 5 4 LSD (0.05) 0.4 CV (%) 6.6 Note: Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 107 Table 12 (cont'd.). Intercropped Maize (40,000 pl/ha) with: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Calcium 1984 0.2 0.2 0.1 0.2 (gm/kg) 1985 0.2 0.2 0 2 0.2 1986 92 9.2 9.2 0_.2_ Column Mean 0 2 0.2 0.2 0.2 CV (%) 16.0 Magnesium 1984 2 2 2 2 (gm/kg) 1985 2 2 2 2 1986 2 2 2 2 Column Mean 2 2 2 2 CV (%) 8.8 Boron 1984 2.3 2.4 2.5 2.5 (mg/kg) 1985 2.6 2.5 2 6 2.7 1986 93. 9.3. u 2.9 Column Mean 2.5 2 4 2.5 2.5 CV (%) 15.0 Copper 1984 4.26-d 4.96 3.5d 4.36-d (mg/kg) 1985 4.06-d 4.56-¢ 3.8¢d 3.8¢d 1986 9.769 ad .3._8cd 996d Column Mean 4.3 4.3 3.7 4.0 LSD (0.05) 0.9 CV (%) 16.2 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 108 Table 12 (cont'd.). Intercropped Maize (40,000 pl/ha) With: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Iron 1984 27 30 29 30 (mg/kg) 1985 27 28 25 25 1986 9 22 9 9 Column Mean 29 28 28 29 CV (%) 11 1 Molybdenum 1984 0.3 0.3 0.4 0.3 (mg/kg) 1985 0.5 0.4 0 4 0.5 1986 9.3. 9.3. 0._3 99 Column Mean 0 4 0.3 0.4 0.4 CV (%) 23.7 Manganese 1984* 7 7 7 8 (mg/kg) 1985 5 5 4 4 1986 9 9 9 9 Column Mean 6 6 6 6 CV (%) 13.2 Zinc 1984 32b¢ 376 336b 376 (mg/kg) 1985 319-d 2766 28¢-6 299-6 1986 ggbc age §Qb'e ggc-e Column Mean 32 30 30 31 L50 (0.05) 5 CV (%) 11.0 Note: Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 109 higher than grain copper values of maize in association with Carioca at the same density level in the third season (Table 12). Significant seasonal effects were noted for grain protein, nitro- gen, phosphorus, potassium, magnesium, iron, manganese, and zinc concentrations of maize at the 1 percent and calcium concentration at the 5 percent probability level (Appendix A, Table A9). Grain protein and nitrogen concentrations of maize were generally lower in the first growing season than in the last two cropping seasons. 0n the other hand, grain phosphorus concentration of maize was significantly lower during the third growing season as compared with the first two seasons (Table 12). Grain potassium and manganese concentrations of maize were significantly lower during the second cropping season as compared to the first season (Table 12). Grain potassium concentration of maize in association with Domino was significantly higher than grain potassium values of maize in association with Carioca during the third cropping season (Table 12). Bean cultivars did not affect grain nutrient concentration of maize in associated culture. Similarly, year x density, cultivar x density, and year x cultivar x density interactions were not significant in grain nutrient concentration of maize (Appendix A, Table A9). The comparison of monoculture and associated culture nutrient concentrations indi- cated that the two cropping systems did not differ Significantly in grain nutrient concentration of maize (Table 13). 110 Table 13. Grain Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns. Intercropped Maize (40,000 pl/ha) with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Protein 1984 90 90 90 100 90 (gm/kg) 1985 110 100 100 100 100 1986 .99 m 10.9 19 .190 Column Mean 100 97 97 100 97 CV (%) 7.1 Nitrogen 1984 14 15 15 15 15 (gm/kg) 1985 17 16 16 16 17 1986 9 9 1_7 9 9 Column Mean 16 16 16 16 16 CV (%) 7.1 Phosphorus 1984 6 6 6 6 6 (gm/kg) 1985 6 5 5 5 5 1986 9 9 9 9 9 Column Mean 6 5 5 5 5 CV (%) 7.4 Potassium 1984 5 5 5 5 5 (gm/kg) 1985 5 4 4 4 4 1986 9 9 9 9 9 Column Mean 5 5 4 5 4 CV (%) 6.3 111 Table 13 (cont'd.). Intercropped Maize (40,000 pl/ha) with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Calcium 1984 0.2 0.2 0.2 0.1 0.2 (gm/kg) 1985 0.2 0.2 0.2 0.2 0.2 1986 92 u 0_.2_ 92. 0_2. Column Mean 0 2 0 2 0.2 0.2 0.2 CV (%) 14.2 Magnesium 1984 2 2 2 2 2 (gm/kg) 1985 2 2 2 2 2 1986 2 2 2 2 2 Column Mean 2 2 2 2 2 CV (%) 8.6 Boron 1984 2.6 2.3 2.4 2.5 2.5 (mg/kg) 1985 2.7 2.6 2.5 2.6 2.7 1986 a Q 29 29 29 Column Mean 2 5 2.5 2 4 2.5 2.5 CV (%) 14.5 Copper 1984 4.4 4.2 4.9 3.5 4.3 (mg/kg) 1985 3.8 4.0 4.5 3.8 3.8 1986 99 99 99 .3._9 as. Column Mean 4 0 4.3 4 3 3.7 4.0 CV (%) 15.2 112 Table 13 (cont'd.). Intercropped Maize (40,000 pl/ha) with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Iron 1984 32 27 30 29 30 (mg/kg) 1985 26 27 28 25 25 1986 9 9 22 9. 9 Column Mean 30 29 28 28 29 CV (%) 10.3 Molybdenum 1984 0.2 0.3 0.3 0.4 0.3 (mg/kg) 1985 0 5 0.5 0.4 0.4 0.5 1986 0_.3_ u. 9.9 9.9 99 Column Mean 0 3 0 4 0.3 0.4 0.4 CV (%) 10.3 Manganese 1984 7 7 7 7 8 (mg/kg) 1985 5 5 5 4 4 1986 9 9 9 9 9 Column Mean 6 6 6 6 6 CV (%) 12.7 Zinc 1984 33 32 37 33 37 (mg/kg) 1985 32 31 27 28 29 1986 28. 3_2 9 9 9 Column Mean 31 32 30 30 31 CV (%) 10.7 113 4.5.2. Maize Leaf Mineral Nutrient Concentration Results of leaf nutrient concentration of maize in associa- tion with bean cultivars are presented in Appendix A, Table A10. Leaf manganese concentration of maize was the only nutrient which was Significantly affected by bean cultivars at the 1 percent probability level (Appendix A, Table A10). Manganese concentration of maize leaf produced in association with Carioca was signifi- cantly increased over maize intercropped with Domino (with one exception) during the third cropping season (Table 14). Highly significant seasonal effects were observed for leaf phosphorus, potassium, calcium, magnesium, boron, copper, iron, molybdenum, manganese, and zinc concentrations of maize and for nitrogen concentration at the 5 percent probability level (Appen- dix A, Table A10). Leaf phosphorus, calcium, magnesium, copper, iron, molybdenum, manganese, and zinc concentrations of maize were significantly lower during the second growing season than in the third cropping season (Table 14). A significant effect of bean density on leaf nutrient concentrations was noted for calcium and boron concentrations of maize at the 5 percent probability level (Appendix A, Table A10). Calcium and boron concentrations of maize were generally higher at 100,000 bean plants/ha than at 200,000 plants/ha. Cultivar x density interaction was Significant (p < 0.05) for leaf phosphorus and boron concentrations of maize. Maize associated with 100,000 Carioca plants/ha had Significantly higher leaf phOSphorus and 114 Table 14. Leaf Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Associated Culture. Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Nitrogen 1984 23 26 28 23 (gm/kg) 1985 30 32 28 28 1989 9 9 9 29 Column Mean 29 31 28 27 CV (%) 21.5 Phosphorus 1984 4C 5b 4¢ 4¢ (gm/kg) 1985 4C 46 4c 4C 1986 9b 9a 9b ‘éb Column Mean 4 5 4 4 L50 (0.05) 0.6 CV (%) 10.5 Potassium 1984 23 25 22 22 (gm/kg) 1985 20 22 21 22 1986 9 9 9 9 Column Mean 22 25 23 23 CV (%) 13.8 Calcium 1984* 8 8 7 7 (gm/kg) 1985 7 6 6 7 1986 9 99 9 9 Column Mean 8 8 7 7 CV (%) 12.8 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 115 Table 14 (cont'd.). Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Magnesium 1984* 5 5 5 5 (gm/kg) 1985 5 4 4 4 1986 .5. 2 .5. .5 Column Mean 5 5 5 5 CV (%) 14.3 Boron 1984 lzab 13a 12ab 11bc (mg/kg) 1985 lzab 12ab 11bc 11bc 1935 _2d llbc lQCd _2d Column Mean 11 12 11 10 LSD (0.05) 2 CV (%) 11.5 Copper 1984* 16 16 14 15 (mg/kg) 1985 12 14 13 13 1986 17 20 18 19 Column Mean 15 17 15 16 CV (%) 11.6 Iron 1984* 130 140 128 124 (mg/kg) 1985 105 109 101 108 1986 w m m 95. Column Mean 125 137 125 126 CV (%) 9.0 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 116 Table 14 (cont'd.). Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) 100 200 Trait Year Domino Carioca Domino Carioca Molybdenum 1984* 5.2 5.4 4.8 5.1 (mg/kg) 1985 4.4 4 1 4.1 4.5 1986 u 22 £9 9.2 Column Mean 5 2 5.5 5.1 5.3 CV (%) 11.3 Manganese 1984 410d 48C 39d 406d (mg/kg) 1985 17e 20e 18e 20e 1935 Qfib Zia QQb égab Column Mean 40 47 39 42 LSD (0.05) 9 CV (%) 14.5 Zinc 1984* 60 62 57 57 (mg/kg) 1985 44 47 46 50 1986 1.2. .72 a 6_9 Column Mean 59 63 59 59 CV (%) 14.9 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. Year marked with an asterisk (*) is significantly (p < 0.05) different from other years. 117 boron concentrations than at 200,000 Carioca plants/ha during the first and third growing seasons (Table 14). Year x cultivar, year x density, and year x cultivar x density interactions for the con- centration of maize leaf nutrient were not significant (Appendix A, Table A10). The comparison of leaf nutrient concentration of maize in associated culture and monoculture- systems indicated that leaf nitrogen, potassium, calcium, magnesium, copper, and zinc concen- trations of maize did not differ significantly (Table 15). How- ever, significant differences were observed in leaf phosphorus, boron, iron, molybdenum, and manganese concentrations of maize at the 5 percent probability level. Leaf phosphorus concentration of maize in monoculture was significantly lower than the concentration in maize leaves produced in association with Carioca at 100,000 plants/ha in the third cropping season (Table 15). Similarly, boron concentration of maize leaf in association with Carioca at the lower density in the first growing season was significantly higher than leaf boron concentration of maize under monoculture (Table 15). On the other hand, leaf iron and molybdenum concentrations of maize in the monoculture were either not significant or signifi- cantly higher as compared with corresponding values in associated culture. Leaf manganese concentration of maize in the monoculture and in associated culture were not significant in the first two growing seasons, while in the third cropping season, manganese 118 Table 15. Leaf Nutrient Concentration of Maize as Affected by Year, Bean Cultivar, and Bean Density in the Two Cropping Patterns. Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Nitrogen 1984 29 23 26 28 23 (gm/kg) 1985 26 30 32 28 28 1986 22 3_4 as .22. 2.2 Column Mean 29 29 31 28 27 CV (%) 23.1 Phosphorus 1984 5b 4c 5b 46 4c (gm/kg) 1985 4c 4C 4C 4C 4c 1935 Eb ‘fib Qa ‘éb §b Column Mean 5 4 5 4 4 LSD (0.05) 0.6 CV (%) 9.6 Potassium 1984 25 23 25 22 22 (gm/kg) 1985 19 20 22 21 22 1986 29 a 2_7 2a .29 Column Mean 24 22 25 23 23 CV (%) 12.9 Calcium 1984 8 8 7 7 (gm/kg) 1985 8 7 6 6 7 1986 2 a E a a Column Mean 8 8 8 7 7 CV (%) 13.6 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 119 Table 15 (cont'd.). Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Magnesium 1984 5 5 5 5 5 (gm/kg) 1985 5 5 4 4 4 1986 9 .9 9 9 9 Column Mean 5 5 5 5 5 cv (%) 14.5 Boron 1984 11bc 1zab 13a 12ab 11bc (mg/kg) 1985 1ocd 1zab 12ab 11bc 11bc 1935 lQCd _2d llbc lQCd _2d Column Mean 10 11 12 11 10 LSD (0.05) 2 cv (%) 11.3 Copper 1984 16 16 16 14 15 (mg/kg) 1985 13 12 14 13 13 1986 99 91 99 19 19 Column Mean 16 15 17 15 16 cv (%) 12.9 Iron 1984 144b-9 130$!-f 1406:e 1289-9 124f-h (mg/kg) 1985 1139-1 1051 109h1 1011 1081 1986 flab 9116-9 ma 993-6 19'” Column Mean 139 125 137 125 126 LSD (0.05) 15 cv (%) 8.4 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 120 Table 15 (cont'd.). Maize (40,000 pl/ha) Intercropped with: Bean Density (103 pl/ha) Sole Maize 100 200 Stand Trait Year (40,000 pl/ha) Domino Carioca Domino Carioca Molybdenum 1984 5.9b-d 5.26-f 5.4b-e 4.89'9 5.1d-f (mg/kg) 1985 4.49'9 4.49'9 4 19 4.19 4.59'9 1986 996 um 99a 99” flab Column Mean 5.7 5.2 5.5 5.1 5.3 LSD (0.05) 0.9 CV (%) 12.1 Manganese 1984 47d 41d 48d 39d 40d (mg/kg) 1985 15e 17e 20e 18e 20e 1935 Ziab ggbc Zia QQC gga-c Column Mean 45 4O 47 39 42 LSD (0.05) 10 CV (%) 16.3 Zinc 1984 68 6O 62 57 57 (mg/kg) 1985 48 44 47 46 so 1986 19 2.2. 7_9 .79 .69 Column Mean 65 59 63 59 59 CV (%) 14.1 Note: Numbers with the same letter(s) are not significantly dif- ferent from each other at the 0.05 level. 121 concentration of maize leaves produced in monoculture was either not significant or significantly higher than in the intercropping systems (Table 15). CHAPTER 5 DISCUSSION 5.1. Bean Performance in the Two Cropping Systems In Carioca, nodes per plant, stem thickness, and plant height appeared to decrease with increasing plant density. 0n the other hand, pods/m2, leaf area index, biomass, and seed yield increased with increasing plant density although seed yield was not signifi- cantly affected (Table 16.1), as reported by Edje and Laing (1982) and Mmbaga et al. (1982). Seeds per pod and hundred seed weight did not differ significantly despite varying bean densities, indi- cating that shading due to maize and bean density did not affect the performance of these two yield components. Beans were able to compensate for these yield components. Similarly, stem thickness and nodes per plant in Domino decreased as the bean density increased, indicating that plant c9fl299191999for9119ht_hand moisture was greater at higher bean densities as compared to lower ones (Table 16.2). Furthermore, shading might cause development of thinner _and smaller leaves compared to monocultural leaves, thus reducing the volume of photosynthetic cells per leaf (Wilson and Cooper, 1960). Shading of beans by maize plants during later growth probably reduced the supply of photosynthate for the developing seed (Fisher, 1979). However, plant height, seeds per pod, harvest index, and hundred seed weight in Domino were not greatly affected by maize shading 122 123 Aoofiv mm AooHv mm Aeofiv 4N mm Asmv oem_ez vmmm umgucsz fifimv we Aemv em Ammv em am 999 xeeee “moseez Aemv New Ammv we“ Ammv wee moem Aee\mxv e_o_> eoom Aeev wefi Aeev «ea Ammv Hmfl men A~e\mv mmeee_m “Nev m.N Akev o.N Amev m.fi o.m xeeee eoe< Lee; Ammv m.e Away 0.8 Ammv m.e m.e eee\meeom Ammv N99 Ammv mofi Aomv om New ~e\meea Afimv KN Ammv mm Amev mm mm Aev eoeeaooeoeefi eem_9 o>_ue_om Away me Acofiv me Amofiv mm me Asov peace: eee_a Ammv m9 Amav mH Aooflv 4H 49 eee_e\moeez Ammv Ne.o Ammv me.o Aemv we.o 9m.o Asov mmeexo_ee eoem mgappsuocoz com mgappauocoz omH menu—auozoz oo~ com mp_mg» ea 9 co 9 co & muowcmu Ams\_q moHv mmwpwmcmo euowgmu umqaocugmucn —ec=u_:oo:oz mamumxmlm:_ammuu .mc=u_:u umuowuomm< :_ use menu—soccer =_ mu_mch muo_gcu $0 :omPLquou .H.oH m_nm» 124 Aoev NH Aomv m om Aee\mxv e=_mmeeee Aemv e ANNV m 99 Aee\axv aseeeaaeea Aemv mm Ammv em mofi Aee\mxv eomeee_z Aemv mmm Ammv NHN Nee Aee\mxv e_aeeea Ammv mm Aemv Hm Ammv me mew A~e\5mv Hem_oz ago 6669 Amev em Amev om Aemv Ne eHH Ame\5mv pgmpmz xgo mm>mm4 “Nev we afiev Ne Aemv em fiofi ANe\Emv eem_ez sea seem Aomv m Aoev e Aoav a CH A~e\Eav Hem_ez ago poem mc:u_=uo:oz com menu—zuocoz omH mg=u_:uo:oz ooH com mp_mch co 9 ea 9 co 9 muo_cmu Aec\_a mofiv movachma muo_gmu umaaogogmucm _mg:u_:uo:oz mamumam mcwqqmgu .A.e.eeoov H.eH e_eee 125 Aoofiv 0H Aoofiv mH Ammv mH ma AEQV oem_oz ummm cmcucaz Ammv mm Ammv em Amav em ca 999 xoee_ emesee: Ammv “mm Ahmv mam Ammv wee omem Aee\mxv e_ee> eoom Aeev omfi Aeev Nae Ammv emfi moe Ame\mv wease_m Afiev o.~ Aflev o.N Aemv w.H m.m xaeee eee< eeoA Aemv 2.0 Aoofiv m.e Away m.e m.e eea\meeom Aomv NmH A449 emfi Aemv mofi mom Ne\meea Aeev RN Aeev KN Aeev mm em Rev ee_eeeoeoeeH oem_9 oseee_em Aoofiv mm Away mm Aooflv mm mm Asov pea_a: eee_e Aemv NH Ammv m9 Ammv Ma 49 eee_a\meeoz Amev 04.0 Amev mm.o Ammv mm.o Ne.o Asov amoe9o_ee seem mgaupauocoz com mcaupaoocoz om“ mgaupzuocoz ooH com ma_mgh mo & eo & we a o:_Eoo Am;\_a moHv mm_u_mcmo o:_eoo uoaqocuswucm Fecappauocoz mamamam mcwmaogo .mcaa—zu umumwuomm< :_ use ogzupzuocoz :_ muwech o:_soo eo com_goasou .N.oH m_amh 126 Afiev mH Aemv HH mm Aee\mxv e=_maeeoe Amev m Aemv e H“ Aee\mxv aseeeemeee Aoev me Ammv mm eofi Aee\mxv eemeeeez Afiev New Ammv mHN Nee Aee\mxv eeeeeee afiev NHH Awmv No9 Ammv em CNN ANe\5mv eem_ez sea mega Amev em Amev Hm Remy Ne mHH A~e\e@v u;m_m3 age mm>mm4 “Nev me 9449 me Aemv mm moH ANe\e@v eem_oz 92o seem 9549 a 9949 w Aemv N m.mH ANe\EmV eem_ez sea poem menu—soocoz oom mgzg—zuocoz omH mg:u_:uo:oz ooH com mu_mcp mo & we a mo & o=_Eoo Ae;\_a mofiv mm_uwmcma ocwsoo umaaogucmucm .mszupsuocoz mamumaw mcwaqogu .A.e_eeoov N.eH o_eee 127 and density levels, indicating that these traits were stable even under the less favourable growing conditions and were similar to their monocultural values. Eriksen and Whitney (1984) observed that shading decreased pods per plant, but did not affect plant height and seeds/pod of bush beans significantly. As in Carioca, pods/m2, biomass and seed yield in Domino, and to a certain extent, leaf area index, increased with increasing bean plant density. This observation indicated that the optimum values of. these traits depended greatly on the bean density, being highest at the highest bean density although it might not be significantly different. Bean stem and leaf dry weights at three bean density combina- tions with intercropping reached their highest accumulation level during the mid-pod filling phase and declined as physiological maturity was approached (Figures 1 and 2), indicating an assimilate remobilization from these plant parts to the developing pod and seed. Leaf senescence might also contribute to the decline of stem and leaf dry weight at physiological maturity. Since photosynthate transport from the leaves was reduced at this phase of plant development due possibly to aging leaves, the consequence was reduced leaf area index for optimum photosynthesis. However, weight of roots of both cultivars at different den- sities under intercropping was similar throughout the reproductive stages (Table 2; Figure 3), indicating that remobilization of dry matter from roots did not play a major role in seed filling and development. It might be more efficient if the plant translocates 128 assimilates from leaves and stems to the developing pods and seeds rather than transfers stored assimilates from roots to the seed. The plant might need more energy to transfer root assimilates to the reproductive organs. Furthermore, it might also be possible that there was limited demand for more assimilates from the roots, indicating that the bean plant in associated culture might have only a few pods and seed and therefore the assimilates from stem and leaves were probably adequate to meet the demands for seed filling. However, bean reproductive organs under monoculture were significantly higher than those in associated culture. Con- sequently, root assimilates were transferred to pods and seeds and thus root dry weight of both cultivars declined towards physio- logical maturity. Burga (1978) indicated a movement of assimilates from leaves to stem and then to the pods. Edje and Laing (1982) observed that in bean-maize association bean dry matter distribution for leaves, stems, and pods was 33, 45, and 2 percent, respectively, while monocultural dry matter distribution was 41, 33, and 4 percent, respectively at 58 DAP. Adams et al. (1978) indicated that the inability of remobilization of starch from roots and stems could result in low rates of seed filling and consequently low seed yield. Roots accumulated 45 percent of the translocated C14 throughout the life of the node four leaf (Waters et al., 1980). About 80 percent of the C14 activity exported from node eight at flowering was in the middle and upper stem sections, but during 129 pod-filling over 85 percent moved into the pods and less than 1 percent to the nodulated root system (Waters et al., 1980). Seed yields of bean in associated culture ranged from 29 to 34 percent and 28 to 35 percent of their monocultural yields for Domino and Carioca, respectively, for the 1984 growing season. However, seed yield of Domino for the second cropping season ranged from 49 to 59 percent while seed yield of Carioca was only 48 per- cent of their seed yield under monoculture at different bean densi- ties. In the third growing season, seed yield of both cultivars grown in association with maize ranged from 25 to 34 percent of their seed yield under monoculture. Francis et al. (1982b) noted that simultaneous sowing resulted in a 51 and 31 percent yield reduction for beans and maize, respectively. Seed yields of bean in associated culture in the second and third cropping seasons were less than a metric ton, possibly due to moisture shortage in 1985 and common blight outbreak in the 1986 growing season. The unfavourable growing conditions in 1985 occurred just after the bean flowering stage and caused flower and pod abortion and greatly reduced seed yield to one-half or even to one-third the yield of the 1984 cropping season. Lack of moisture in the 1985 growing season also drastically reduced leaf area index (40-50 percent), biomass (40-50 percent), and pods/m2 as compared to the 1984 season, resulting in reduced bean seed yield. Common blight infestation on beans in the 1986 season had a similar effect on bean seed yield. Moisture stress during the 1985 cropping 130 season slightly affected the uptake of bean leaf manganese, calcium, and magnesium though it was not significantly different from the other growing seasons (except for manganese). Since magnesium is a component of the chlorophyll molecule, the photo- synthesis rate might be reduced because of a reduced chlorophyll per unit area, leading to lower assimilates for seed filling. A similar trend for magnesium was observed in the third growing season (Table 9). Leaf molybdenum in the second season was sig- nificantly lower than in other cropping seasons, indicating that bean root nodule ability to fix atmospheric nitrogen was probably adversely affected because molybdenum plays an essential role in N fixation. Nevertheless, macro and micronutrients were sufficient for normal growth and development and therefore could not be responsible for the low yields produced in the second and third seasons. Bean seed protein, N, P, and K yields in monoculture during the first and third growing seasons were three-fold higher than their yields in associated culture, possibly due to high yield components associated with the monocultural system. Seed yield of bean was positively and significantly correlated (0.339,* 0.785,** 0.886,** 0.902**) with seeds per pod, leaf area index, biomass, and pods/m2, respectively, indicating that these traits probably *Indicates significance at the .05 level. **Indicates significance at the .01 level. 131 contributed to the final seed yield. Bean seed yield was nega- tively, though not significantly, correlated (-0.220) with seed protein concentration. As expected, biomass was negatively and significantly correlated (-0.263*), with bean percent protein, whereas biomass was positively and significantly correlated (0.306,* 0.842,** 0.842**) with seeds per pod, LAI, and pods/m2, respectively. Hundred seed weight was positively but not signifi- cantly correlated (0.135, 0.033) with seed yield and biomass, respectively, indicating that the final seed yield was not closely related to this yield component. As pointed out earlier, leaf area index of the 1985 and 1986 cropping seasons was significantly less (with few exceptions) than in the first (1984) growing season (Table 3). Maize shading and perhaps other competitive interactions resulted in reduced bean leaf area index by 39 to 46 percent for Domino (type II) and by 23 to 37 percent for Carioca (type III) as compared to their mono- cultural values. Reduced leaf size might have intercepted less light for photosynthesis, thus indicating that assimilates were limited for seed filling and development, and consequently resulted in reduced seed yield. Clark and Francis (1985) observed 31 and 22 percent leaf area index reduction by maize associated with bush and climbing culti- vars, respectively. They obtained leaf area indices of 3.1 and 3.9 for intercropped and monocropped bush beans, respectively, while LAI of climbing beans was 3.6 and 4.1 for mixture and monocultural 132 beans, respectively. However, the highest LAI obtained from maize/ Domino was 2.6 compared with monocultural value of 4.2 while Carioca-maize highest bean LAI was 3.3 and monocultural value was 4.3. Leaf area index of less than 3 might signal a marked reduc- tion of leaf surface area for light interception and photosynthesis sufficient to result in a low bean seed yield. A leaf area index range of 3 to 4 appears to be ideal for adequate photosynthesis. However, LAI values greater than 4 could possibly create shading atmosphere which might reduce the amount of intercepted light for photosynthesis. Gardiner and Craker (1981) obtained LAI ranging from 3.70 to 4.49 for intercropping and monocultural beans, respec- tively. Biomass was also reduced during the last two cropping seasons, indicating that bean dry matter accumulation was limited for proper plant growth and development and a reduced biomass yield was reflected by a reduced seed yield for the last two growing seasons (Table 3). Figures 4-8 show the relationship between bean seed yield and bean biomass yield, pod/m2, and LAI; relation between biomass and pod/m2, and LAI over three densities. As the biomass yield increased, so did the seed yield, indicating that optimum biomass production during the vegetative stage would be a prerequisite for improved pods/plant, seeds/pod, seed size, and ultimately increased seed yield. Consequently, seed yield of bean in associated culture decreased possibly due to reduced leaf area index, reduced light interception, biomass yield, and pods/plant. 133 mm_ywmcma pcmgwemwo we comm eo mmmsopm van u_m_> .v mc:m_m Amgmuom:\mu=m_m we mucmmaogbv auwmcmo comm ace one ear r1 _ L 9: lull" ll - 111111. 1111111 109w «4 DC .0. (Q 1.1.1.11 11111 II]! 11111.11 IIIIIIIW . ..... 111111.11 1.1111111. C 2 :2 C D l 06 m #1.... 1111I11¥11111 1 11111111111 ..006 $11111 10mm 1 mee— dUOEdU I111... 111111 1 [1111111 1.11111: '1 11111111 11. 11111. mwizom 811.11 (Pu/54) pla11 (aw/m6) ssewotg 134 8.53:8 peegewwwa we .33 we meee nee 3e; .m 9:5: Aegeuee:\mu:e_e we meeemeeswv xuwmeeo :eem Dam Qmw Dcw H.- _ r1uwh 11r1111111111. .111 11 .. 11.1..- .1111... 1 o m. w (Awamig 11111 111111. . 11LV1 -111.eez;4em 1ene lll‘llll Illllllull m1..- 111111.13. 1 0m. m 'n'llllllfiwl' .11111 10mm $1111.... . . DOG— I111)... --. . .111111111111 ee— ..e.u ...”. Ema m... 111.111.611.111 1111.. T111111 1111111111111 1111111111 IRIILIIILHMII e. . % vll fiunw F 1...... C Z _ F. .. O U llxlhtllnlll. 1111111111111. ..eew fillllllll fil 1 - Cm. P (Pu/54) p131. 135 mewuwmseo usesewwwo we seem we xeusw ees< wees use uwew> .o esemws Aeseuee:\mwse_e we musemeeswv auwmseo seem ODN Om? 00? . _ _ 1% 3 m 11.3.1111 1 1 1.1. 11.11.11 ....1....... 13w .400 E45 - .1111-.. . \ 11.11.111.1NLZ—2PVD WGWM I11." 'Illlsllslik-l 411. 111111111141 1eee 'I‘Iullllllllllll' 111111111 1ewm . 1 omfiz. h.— 111. .11. m.w .. 111111 eéi . 11111111111 Illllllllllll\.\llll\. 11 P H llxlll..|..H|\l .. . x). I 1. .Ju 1111. 59%... 1.. (an/61) p1311 1V1 136 mewuwmsem usesewwwm we seem we muee use mmesewm .w esemwm Aeseuee:\masepe we musemeeswv apwmsem seem mom omw Dow r s _ 9.: ON— 111111111. u1G¢F ..a.ee_e.a.u 1111111111 .111... Tee. 11.11111 1111111111 .. - 111111 11111111111 CE. 5 CD - It! .Icmp .l - _ . 8...... 1111111114 (0. Q _ m {we 11.111111111111111 1.....1 me P #1 1111111111 111.1111 .. :1 1 em. 1111.... 02.2....e 1111511111 1111111111111 1 S 2 11111111 (zw/wfi) ssewotg s 0 2w/ P d 137 mewewmsem usesewwwm we seem we xeusm ees< wee; use mmesewm .m esemwm Aeseuuez\muse_s we musemeeswv xuwmsem seem meow 0.1“: on; _ b 1— 00 P on F 111111111111 e: .4395 11.111111. 1.111111. 18. 1111111111111 111111111111 J. .111 1.111...- 02.23 .118. 51 r . . new r1m.w I . |lI.I.IILIlII\II\I.I\II\|1I.l||IH\| # m a P cE1111HH11fil1111|floE<1 4 111.11.111.11 1.111111111111111. . al.— ...I P 6N fillllllllllll ..| m 1 N. u r e (am/m6) ssewotg IVl 138 The relative light interception for Domino in association was between 44 and 47 percent of its light interception in monoculture (Table 16.2). The relative light interception of Carioca ranged from 43 to 53 percent of the light readings under monoculture (Table 16.1). This observation indicated that limited light might have resulted in a reduced rate of photosynthesis. Limited light led to reduced seed yield, possibly due to limited assimilates for plant growth, development, and seed filling. Consequently, beans in association with maize had a lower number of pods/plant, biomass yield, and economic seed yield. Similarly, roots, stems, and leaf dry matter accumulation for the two bean cultivars were between 36 and 50 percent of their monocultural dry weight (Tables 16.1 and 16.2), indicating that the environment created by the presence of maize as a companion crop greatly reduced the expression of these traits. The reduction in mean dry matter produced by beans in asso- ciation with maize was probably due to reduced light interception resulting from maize shading and probably due to competition for available soil moisture. The shading of bean plants by maize could have limited the amount of light that was available for inter- cropped bean, resulting in a reduced rate of photosynthesis and consequently reduced seed yield. Fisher (1979) observed that beans intercropped with maize never intercepted more than 30 percent of the light. Therefore, limited assimilates affected plant size and yield-related traits. 139 Harvest index (HI) of intercropped beans ranged from 53 to 59 percent while HI of monocultural bean was between 59 and 65 per- cent. However, HI range did not reflect a predictable trend. In most cases, highest HI corresponded with high seed yield. In a few observations, high yielding treatment combinations (953 kg/ha) showed the lowest HI (53 percent) while seed yield of 623 kg/ha had a HI of 58 percent. This observation indicated that HI might not be a reliable selection index for identifying new breeding lines, a view shared by Zimmermann et al. (1984). A negative correlation between grain yield and harvest index was reported by Laing et al. (1980). Clark and Francis (1985) obtained a HI for bush beans ranging from 52 to 56 percent in associated and monocultural systems, respectively. Harvest index for climbing beans ranged from 58 to 62 percent for intercropping and monocultural systems, respectively (Clark and Francis, 1985). 5.2. Bean Carbohydrate Concentration Bean root, stem, and leaf carbohydrates in the second (1985) season were generally higher than the 1984 and 1985 seasons. The results in 1985 could possibly be a consequence of the reduced pod number/plant induced by the severe drought which occurred after flowering. Seed yields of Domino and Carioca grown in monoculture in 1985 were 1,562 and 1,357 kg/ha, respectively, compared to 3,271 and 3,483 kg/ha, respectively, for 1984 and 2,456 and 2,384 kg/ha, respectively, for 1986. The reduced reproductive sink in 1985 may have led to a higher carbohydrate accumulation in root and stem 140 tissues as compared with the other two seasons. Leaf carbohydrate concentrations in the monoculture and intercropping systems were not significantly different and were lower than root and stem con- centrations. This observation indicated that leaves rarely stored the synthesized carbohydrate but instead they constantly trans- located newly synthesized products to stem, pods, seeds, and roots for storage. Root TNC in Domino for the two cropping systems in 1985 was significantly higher (except one treatment) than for Carioca within the same season, indicating that Domino may be more tolerant to severe rainfall shortage, possibly due to a stronger and deeper root system than Carioca. Root dry weight of Domino in monoculture (Table 2) was two-fold the dry weight of Carioca under monoculture. Consequently, it is postulated that Domino was able to obtain moisture from deeper in the soil profile for increased photo- synthesis and therefore produced significantly higher root TNC than Carioca within the same season. Furthermore, seed yield of Domino was slightly higher than for Carioca (Table 3), although the yield difference was not significant. Domino's higher yield provided further evidence that it might be a more useful cultivar in drought-prone areas than Carioca. However, consumers, particularly in Eastern Africa, might not prefer the seed size, colour, and flavour of Domino. Correlation analysis for three seasons indicated that bean seed yield was positively but not significantly correlated with 141 root carbohydrate. Stem and” leaf carbohydrates were non- significantly and negatively correlated with bean seed yield. The correlation results indicated that there was an increased pod number/plant (1984) which remobilized and depleted stored root and stem carbohydrates (sink capacity exceeded the source capacity) for seed filling, resulting in increased seed yield. 0n the other hand, there was a reduced sink capacity in 1985 due to moisture shortage which resulted in high stored carbohydrate in stem and roots. It appeared that pod abortion was more sensitive to drought stress in 1985 than photosynthesis. As a result, root and stem tissues accumulated high amounts of carbohydrate because sink capacity was a limiting factor, resulting in reduced seed yield. In both cases, seed yield might be poorly correlated with root and stem carbohydrates. High pod number/plant accompanied by high rates of carbo- hydrate storage and remobilization from root and stem tissues for seed filling might strike a balance and increase seed yield. Increased availability of carbohydrate within the plant tissues would be required for increased seed yield. Sinclair and de Wit (1976) observed that soybeans are self-destructive since they need to translocate large amounts of nitrogen from vegetative tissues during seed-fill to promote protein formation and seed growth. They further noted that increased nitrogen supply lengthens the period of seed development and results in substantial soybean yield increases. Screening and selecting bean cultivars with high 142 translocatable root and stem TNC might be a step in the right direction in the immediate future in order to increase bean seed yield in the two cropping systems. 5.3. Performance of Maize in the Two Cropping Systems Neither environmental effects, bean cultivars, nor bean densities affected hundred maize kernel weight, indicating that maize was competitive and efficient in obtaining the essential resources for proper growth and development. Since bean cultivars were approaching physiological maturity, were shorter, less vigorous, and with less root distribution than maize, maize grain size in monocultural maize was not significantly different from grain size of the intercrop maize. This observation indicated that the competitive ability of maize for both above and below ground resources was superior to that of the bean cultivars. 0n the other hand, resources were probably not limiting for growth and development of the maize. Consequently, maize yields in monoculture for the first and the third growing seasons were not significantly different from maize yield in association (with the exception of two maize/Domino combinations which were significantly lower than maize yield under monoculture). Furthermore, grain yield of maize was not significantly affected by bean cultivars and bean densities, probably because the two crop species had different growth durations and therefore wide competitive gap. Thus, each crop reached a peak demand for resources at different times, indi- cating that maize obtained adequate resources for kernel filling 143 and development at the time when beans were approaching physio- logical maturity, an observation supported by Enyi (1973). However, moisture stress of the 1985 cropping season affected maize yield in association with beans, presumably due to lack of adequate soil moisture for normal growth and development of maize plants. Maize yield in associated culture was significantly lower than yield ‘of sole maize stand, probably due to a lower mono- cultural maize plant stand for the available soil moisture (40,000 plants/ha) as compared to that of associated culture (140,000, 190,000, and 240,000 plants/ha) of beans and maize combined. Nutrient concentration in both cropping systems was adequate for grain filling and normal plant development and therefore could not have contributed to lower grain yield of maize in association. Bean cultivars were shorter than maize and therefore would not interfere with light interception of maize leaf. Consequently, limited soil moisture and bean density pressure probably con- tributed to reduced maize yield in the intercrop system during the second (1985) growing season as compared to the 1984 and 1986 growing seasons (Table 11). Maize yield during the 1984 cropping season was 25-30 percent lower than the maize yield of the 1986 growing season, probably due to continuous rainfall during the tasselling stage from which the consequences were fewer kernal numbers/cob and lower grain yield as compared to the 1986 growing season. Kernal number/cob was about 70 percent that of the 1986 kernal number/cob. However, seed size 144 did not differ significantly from the other cropping seasons. Mean yields of maize in the third season were significantly higher than those of the first two seasons, further indicating that poor growing conditions in the first two seasons were responsible for reduced grain yields of maize. A three-year average grain yield indicated that yields of maize were reduced by 15, 14, and 15 per- cent when maize was intercropped with Domino at 100,000, 150,000, and 200,000 plants/ha, respectively (Table 17.1). The maize-Carioca combination at 100,000, 150,000, and 200,000 plants/ha of beans reduced grain yield of maize by 14, 13, and 15 percent, respectively, as compared with monocultural maize. Davis and Garcia (1983) observed 15-30 percent maize yield reduc- tion when intercropped with climbing bean, while Mmbaga (1980) obtained 7-31 percent grain yield reduction compared with mono- cultural maize yield. Maize partial land equivalent ratio when associated with Domino was 0.85, 0.86, and 0.85 at 100,000, 150,000, and 200,000 bean plants/ha, respectively. The Carioca- maize combination provided maize partial LER of 0.86, 0.87, and 0.85 at the same bean density range, though not significantly different from maize-Domino LER. Furthermore, the efficiency of the two bean cultivars in combination with maize peaked at 150,000/ 40,000 plants/ha of bean/maize, respectively (Tables 17.1 and 17.2, and Figure 9). Any maize-bean combination which would not reduce maize yield (primary crop) and provide substantial bean yield (secondary crop) would be a wise investment, and maize (40,000 145 Amev eemm Aeev meoe Amev meme eoos Ae;\mxv e_m_> =_ece m~_ez Ammsv mN.H Aemsv eN.H Aoesv oe.s oo.s Amuse oven“ asmpe>wssm use; Amev me.s flees ee.o Amev me.o oo.s mes _e_eces w~_ez Asmv Hm Asmv mm Asmv Hm em Ages e;m_m3 seem umssszz sees KN sees mm mm Ae;\mxv Ae_e_> s=_mmeuoa Asev Hm Acme mm mm Ae;\mxv upw_> mssossmoss flees em sees mm Nee Ae;\mxv e_ms> cemose_z Aeev cam sees Ham Hes Ae;\mxv e_m_> cemeosa Aemv mes Aemv mes seas ems mes Ages e;m_mz ece_s ms=e_=uo=os sow ms=e_=uo=oz ems ms=e_=uo=oz ooH e;\_s ooo.oe mesesh we & so & es & Aes\~s moHv mmwuwmsmo oswsoo m~_ez su_z Aes\_s ooo.oev «Nee: emssosusmusfi Fes=p_=uosoz msmumam ms_aaosu .msowueswssou os_Eoo\m~wezunms:u—su emue_uomm< s_ use es:u_:uosoz s_ muwesh m~_ez mo som_sessou .H.NH ereh 146 emee meme eeee ecee eeee eeoe eooe ee;\mee eeaee cease seems emmee mN.e eemee «N.e eomee e~.e oo.e eseee oeeem useee>_:cm usee emee me.o eeee ee.o eeee ee.o oo.e see eeeesea «News Acme Ne eemv em eeme Ne em esme enmeaz ueem uesussz emev em emee em mm ee;\mee eeemee ssemmeeoa eeee em eeee em em ee;\mee u_e_> masossmoss eeee em eeee ea Nee ee;\mee eeee> cemoseez emee emm eeee woe eoN ee;\mee eeeee ceeeocs emme eee Acme eee emme eee mme ease enmee: eeees ezaeezuocoz ooe eczeeauocoz ome esaeeauoeoz see e;\ea oeo.oe meeese ea e eo e ea e Aes\_s meev mewuwmseo euo_seu eN_ez su_z Aes\—s ooo.ovv eewez uessosuseuse pessu—zeosoz mseumamlmswaaosu .msowues_nEou eeo_seU\erezuues:ue:o ueee_eomm< s_ use essupseosoz se mu_esh eN_ez mo somwseqsou .N.Ne e_neh 147 me_uwmsem usesemmwm ee eNPez use seem mo u—ew> .m es=m_m Aeseeuez\muse—s eo musemsoshv xewmsem seem ODN 00F _ meme? _ 02 1H .11.. 111111. 111111.:ese I‘I [ll 1111.1 mil...) 11:11.11... l\|\l\l.l.1l.llllll ill {09$xe 11.111. \ 11111.1... AVE—EDD 100m x... eN_<2\ 02.2er 1141/1111 III If” ewes... {8&5 if. .1111... 111.111 / .111-‘1 ll} .uomsm 11.1.. fleece . ..oeoe .IOOFQ e.emMee (Bu/5») 91311 ueaa (cu/5x) P1311 8219w 148 plants/ha) with beans (150,000 plants/ha) met the criteria and consistently offered greater yield than the other density combinations. Nevertheless, bean yields at the three density levels in association with maize had always been non-significant; the finding agreed with Mmbaga et al. (1982). Since doubling bean density from 10 to 20 plants/m2 (100,000 to 200,000 plants/ha) had no signifi— cant impact on bean seed yield, adopting the high bean density would be a waste of seed which is in limited supply for farmers. High bean density reduced maize plant height, maize grain size (Domino-maize combination), and maize grain yield more than any other bean density combination and would not benefit small holders (Tables 17.1 and 17.2). Planting of high density beans would require more labour and/or time which is also scarce and would not be productive for the farmers. Extra seed could be used for food which is limited or for marketing to earn cash for other household needs. Recommending 100,000 bean plants/ha would be taken with some reservation since this combination had a slight reduction on land equivalent ratio, maize grain size (maize-Domino), and maize grain yield as compared with 150,000 plants/ha (Tables 17.1 and 17.2). Lower bean density appeared to have stronger root systems and thicker stems and effectively competed with maize roots for soil moisture for growth and development. 0n the other hand, higher bean densities had weaker root systems and thinner stems than the 149 lower ones. However, due to high plant density, root mass was greatly increased resulting in increased inter- and intra-specific competition for moisture, leading to slightly reduced maize grain yield. At 150,000 bean plants/ha, root development and stem thick- ness appeared to be optimum and both inter- and intra-specific competition was optimum too. This led to less competition for moisture and consequently to higher maize grain yield than the extreme bean densities, though not significantly different. Domino stem diameter at 100,000, 150,000, and 200,000 plants/ha was 88, 78, and 73 percent respectively, while Carioca was 94, 88, and 82 percent of their stem thickness in monoculture. In general, Domino stems were thicker than Carioca and the dif- ference was reflected in the three-year maize grain yield being slightly higher in the maize-Carioca combination than maize-Domino intercrops at 15 bean plants/m2, although the difference was not significant (Tables 17.1 and 17.2). Consequently, a combination of maize (40,000 plants/ha) with beans (150,000 plants/ha) provided a competitive balance between the two crop species and appeared to be superior to the other density combinations (Figure 9) and thus worth recommending to farmers in Tanzania. Nevertheless, combined yields produced from Tanzania might be relatively lower than yields produced in East Lansing due possibly to disease and pest infesta- tion, unfavourable weather, poor soil fertility and crop husbandry, and low yield potential of the indigenous cultivars. Thus, 150 recommendations based on experiments in East Lansing might not be truly appropriate for Tanzanian conditions. Protein, N, and P yields of maize in monoculture during the first and third cropping seasons were not significantly different from their corresponding maize yields in associated culture (with few exceptions), showing that growing conditions in mixtures were probably not unfavourable for maize growth. Height of maize was significantly and positively correlated (0.598**) with maize grain yield. However, kernel weight and land equivalent ratios were positively but not significantly correlated (0.048, 0.145), respec- tively, with maize grain yield. In contrast, bean biomass was significantly correlated while bean seed yield was not signifi- cantly correlated but both were negatively correlated (-0.384,** -0.199, respectively), with maize grain yield. Bean densities affected land equivalent ratio (LER) for maize-Domino and maize-Carioca combinations. Land equivalent ratio and bean seed yield increased with the increasing bean densities for both bean-maize combinations, being highest at the highest bean density (200,000 plants/ha). It appeared that intercropping effi- ciency was determined by bean yield and not by the yield of maize. Mmbaga et al. (1982) observed a similar trend in bean-maize density studies at Lyamungu, Moshi, Tanzania. Highest three-year average intercropping efficiency (LER 1.29) was obtained when maize was intercropped with Domino at 200,000 plants/ha, probably due to efficient use of light and soil resources. High root mass at this 151 density combination of 40,000 maize plants/ha plus 200,000 bean plants/ha was probably able to extract nutrients and moisture from different soil profiles for grain filling and ultimately seed yield. Furthermore, at this density combination, plants were capable of covering the ground early in the season and possibly intercepted more light for photosynthesis and the stored assimilates were used for plant growth and development and for grain filling. High LAI, which is associated with high bean density, could have shaded the soil and helped control weeds and reduce loss of soil water by evapotranspiration. Soil water saved from evapotranspiration would be beneficial to cr0p components in association. At the lower plant density combinations, resource waste might have occurred due to less ground cover to capture more light and reduced root mass to exploit soil resources. Land equivalent ratio for the testing period ranged between 1.15 and 1.35, while Mmbaga (1980) obtained LERs ranging from 1.04 to 1.34 at the same location but with different bean and maize cultivars. Intercropping work at Lyamungu, Moshi, Tanzania produced LERs ranging from 0.96 to 1.58 (Mmbaga et al., 1982). Francis et al. (1982) obtained LER values of 1.52, 1.47, and 1.35 when maize was simultaneously intercropped with bean types I, II, and III, respectively. Combined maize-bean yields were between 6,767 and 6,941 kg/ha while half hectare yields of each monocultural crop ranged only between 4,707 and 4,718 kg/ha. The highest monocultural yield was 152 7,006 kg/ha (Table 18.1; Figure 10), thus not in keeping with the hypothesis that combined intercrop yield would be higher than the best monocultural yield (Table 18.1). On the other hand, combined intercrop yields of the component crops were higher than their com- bined monocultural component crop yields (4,707 and 4,718 kg/ha), thus lending support to previous hypotheses _(Table 18.1). Bean cultivars provided an appreciable combined maize-bean yield at 40,000/150,000 plants/ha maize-bean density combination, respec- tively, indicating that the density combination would be suffi- ciently productive to provide support for the homestead families in developing countries. Francis et al. (1982) obtained highest total grain and protein yields at a density combination of 3 to 4 and 10 to 15 plants/m2 for maize and beans, respectively. Even though maize yield under monoculture was higher than any intercrop yield combination, an associated culture system is still more important than sole maize stand because mixtures of maize-bean provided high protein yield (Table 18.2). Protein plays an important role in human growth and development and legume seeds are nearly always a component of the human diets in most developing countries. Table 18.2 shows the three-year average of combined maize-bean protein yield ranging from 810 to 870 kg/ha in associated culture, whereas monocultural combined protein yield ranged from 671 to 681 kg/ha. The best monocultural protein yield (701 kg/ha) was always lower than combined protein yield in associated culture, thus supporting the hypothesis that combined yield in association 153 Table 18.1. Three-Year Average Yield of Bean and Maize as Affected by Bean Density. Intercropped Maize/Bean Combinations kg/ha Density (103 pl/ha) Domino Maize Total Carioca Maize Total 100 779 5988 6767 768 6028 6796 150 893 6023 6916 776 6104 6880 200 957 5984 6941 887 5945 6832 Monoculture 2430 7006 4718* 2408 7006 4707* *Half monocultural bean and half monocultural maize yield. Table 18.2. Three-Year Average Protein Yields of Bean and Maize as Affected by Bean Density. Intercropped Maize/Bean Combinations kg/ha Density (103 pl/ha) Domino Maize Total Carioca Maize Total 100 219 591 810 212 604 816 200 272 590 862 239 631 870 Monoculture 662 701 681* 642 701 671* *Half monocultural bean and half monocultural maize yield. 154 2.39am mspssosm 2: es”. 5 e~_ez use seem mo eesessotes .3 e25: Aeseuue:\mese—s yo musemsoshv auwmsem seem DON 0m. 00. 02.1.5 maze... ease DU \ . . . e 0258 E e. fix \ \x \ . .. {8&6 E x x x e .e \ \x \\\ \\\ .1oeee \ x _ . ex 1 \ \ \.\\ rose“ \xx... KV»\\ \ l .\ a , e. \M s A...“ \ \ Y 180.». \ . \ C \ . \x A _ \ \‘x. ' ‘x\\ "x. \ \ e \ . e . louse \ .5‘-,_ \. \g‘\ ‘5‘ ‘q ‘\ \ ‘k X 55.4 5 "'5, “'- .. \. ‘\ 5“ “bk x .X -\e 7“” Y. llh.\‘ 7" \q x x. .\ \.\\\\ x e e \ 1 x week ,Le \ -Qse u. Ivy.” .. wxmg I...“ .. mmmemmn .x. _mumxxx. -11. _ \ recon (av/64) plaLA 155 would be higher than monocultural component crops or higher than the best monocultural yield due to more efficient use of natural resources. Latham (1971) indicated that 65 g of protein were required daily for a 55-kg active man. Therefore, protein yield/ha in associated culture would be adequate to feed 34 to 37 adult men for one year while protein yield under monoculture would be enough to feed only 28 to 29 men annually. 810 kg/ha x 1000 g_ 65 g x 365 days/year 870 kgjha x 1000 g 65 g x 365 days/year 37 men = 34 men 671 kg/ha x 1000 gf- 65 g x 365 days/year 681 kg/ha x 1000 9 65'9 x 365 days/year 29 men 28 men Mmbaga (1980), in the same location but with different cultivars, obtained protein yields of combined maize-bean in association which were sufficient to feed 39 to 49 men yearly while monoculture produced enough protein to feed only 38 men for the same period. Edje et al. (1979) obtained similar results in their maize-dwarf beans intercrop trials in Malawi. Hhen Domino was intercropped with maize, protein yield was between 810 and 862 compared to monocultural yield of 681 kg/ha, giving protein yield advantage of 19 and 26 percent while the protein advantage obtained from Carioca-maize association (816-870 kg/ha) was 22 to 30 percent higher than the monocultural protein yield (671 kg/ha). Protein and/or nitrogen content of the maize grain and maize leaf were not significantly different from the monocrop maize, 156 indicating that nitrogen excretion from bean roots and the uptake of the excreted bean nitrogen by maize roots did not occur. However, legume residual N could benefit succeeding non-legume crops. The greatest advantage of the maize-bean association was the increased combined protein yield which was due to a function of high maize yield in addition to bean yield in the intercrop rather than due to nitrogen transfer from legumes to non-legumes within the same growing season. The protein production is essential for daily human needs, especially in the developing world. Inter- cropping beans with a highly competitive cereal like maize, in addition to high total combined plant densities, might create unfavourable conditions for beans, consequently resulting in failure of beans to fix sufficient atmospheric nitrogen for their growth and development and the additional N for the companion crop. Furthermore, bean cultivars used in this experiment might not have the ability to fix nitrogen under the maize-dominated environment, resulting in reduced bean yield in associated culture. Graham and Rosas (1978) observed that N2 fixation by climbing bean (cv. P590) was essentially unaffected by intercropping with maize. Wahua and Miller (1978a, b) noted that shading by the cereal reduced both the seed yield and N2 fixation. The transfer of N from cowpea to maize in association was not evident from either the field or the greenhouse pot studies by Ofori and Stern (1987). On the other hand, Eaglesham et al. (1981) presented evidence from the field of transfer of N from legume to an 157 intercrop cereal, using the N15-labeled fertilizer method. Nair et al. (1979) found a mean wheat yield increase of about 30 percent after a maize-soybean intercrop, and after maize-cowpea, the yield increase was 34 percent when compared to wheat after sole crop maize. De (1980) found that blackgram intercropped with either maize or sorghum improved succeeding wheat yield. Searle et al. (1981) found N uptake of wheat following maize-groundnut and maize- soybean intercrop systems to be higher than after maize alone. 5.4. Plant Nutrient Concentration 5.4.1. Bean Nutrient Concentration Bean seed and leaf nitrogen concentrations in plants grown in association were not significantly different from that in plants grown in monoculture, indicating that nitrogen was not a differen- tiating factor during the trial period. Crop species in both cropping systems were capable of taking up adequate amounts of N for seed filling. It appeared that even the dry conditions of the 1985 season did not affect the N uptake of the two bean cultivars. Bean roots in monoculture and in association with maize were probably dense enough to capture an adequate amount of nitrogen for plant growth and development. Bean densities did not affect nitrogen uptake of the two bean cultivars, indicating that there was adequate nitrogen in the soil for the varied population densities. Nutrient sufficiency ranges for dry edible beans at the upper fully developed leaf sampled prior to initial flowering were 42 to 158 55 gm/kg (1% = 10 gm/kg) for nitrogen (Vitosh et al., 1978). Nitrogen concentration for Domino and Carioca fell within the nutrient sufficiency range (Table 9). Nutrient sufficiency ranges for dry edible beans (2.5-6.0, 17-30, 3.5-20, and 2.5-10 gm/kg for P, K, Ca, and Mg, respectively) were similar to values obtained during the experimental period. However, phosphorus concentrations for the bean leaf and seed and magnesium concentration for bean seed were constant throughout the three growing seasons while bean leaf potassium, calcium, and magnesium concentrations changed with the variation in the environment (Table 9) though not significantly. Bean leaf potassium concentration was higher during the moisture stress of the 1985 growing season and the disease attack of the 1986 season. Calcium uptake was greatly affected by the severe moisture shortage of the 1985 growing season but not by disease pressure of the 1986 cropping season. Calcium uptake of the 1984 and 1986 growing seasons was almost twice the amount absorbed during the 1985 cropping season (Table 9), indicating that bean plants might be deficient in calcium during dry conditions and in turn affect seed filling and eventually bean seed yield. Mag- nesium concentration was also affected by drought and to a lesser extent by disease infestation although not significantly different. Magnesium concentration of the 1984 growing season was almost two- fold the amount of magnesium in the 1985 cropping season. 159 Micronutrient concentration of bean seed indicated that there was no competition between maize and bean cultivars for boron, molybdenum, zinc, and copper nutrients. Since the concentration of these elements in the monocrop beans was not significantly differ- ent from the concentration in the associated beans, it appeared that competition for these elements was at a minimal level. Fur- thermore, moisture and disease stress did not seem to affect the boron, molybdenum, zinc (Table 7), and copper (Table 9) concentra- tions of bean seed since their concentrations remained constant during the three cropping seasons. Nutrient sufficiency ranges for dry edible beans for the upper fully developed leaf sampled prior to initial flowering were 20-100, 50-450, 15-50, 10-30, 20-70, and 1-5 mg/kg (1 ppm = 1 mg/kg) for Mn, Fe, B, Cu, Zn, and Mo, respectively (Vitosh et al., 1978). The experimental bean leaf nutrient concentration data indicated that all the microelements were adequate in the soil and therefore competition for these elements was highly unlikely. 5.4.2. Maize Nutrient Concentration Bean cultivars and densities did not affect maize grain protein, nitrogen, phosphorus, potassium, calcium, magnesium, or the micronutrient concentrations of the kernel. Since protein and nitrogen concentrations of the associated maize kernel were not significant as compared with monocultural maize, it seemed that neither competitive depression from bean plant nor nitrogen transfer from the bean cultivars occurred in the associated maize 160 crop. Macro and micronutrient concentrations remained constant throughout the trial period, indicating that bean cultivars and densities had no significant effect on the maize grain nutrient concentration. It appeared that soil nutrients were available in sufficient amounts for the two crop species; otherwise, competition for these nutrients would have occurred and the concentration differences of maize grain in the two cropping systems would have shown clearly. Competitive pressure from bean cultivars at dif- ferent densities for the soil elements was either at a minimum or did not exist; otherwise, maize grain nutrient concentration in the two cropping patterns would not be similar. Dahl et al. (1982) conducted various experiments under various irrigation, mulch, tillage, and fertilizer levels at the Michigan State University Agronomy Farm. They obtained elemental composition of maize grain ranging from 9.9 to 16.6, 3.4 to 5, 4 to 5.4, 0.05 to 0.06, and 1.4 to 2.2 gm/kg for N, P, K, Ca, and Mg, respectively. Microelement composition ranged from 2 to 4, 2 to 3, 24 to 38, 5 to 11, and 23 to 40 mg/kg for 8, Cu, Fe, Mn, and Zn, respectively. Their finding supported maize grain elemental compo- sition results in Table 13, indicating that the macroelements were sufficiently high while the microelements were either moderately sufficient or sufficiently high. Macroelements were probably adequate for maize grain filling and therefore contributed to high grain yield. Similarly, micronutrients were within the optimum range and thus supported normal maize grain filling and yield. 161 Bean cultivar and density did not affect maize leaf nitrogen, potassium, calcium, magnesium, copper, and zinc concentration since monocultural results were not significantly different from the associated culture results. Furthermore, soil moisture stress during the 1985 cropping season lowered uptake of phosphorus, copper, iron, molybdenum, manganese, and zinc as compared to the first and third growing seasons. Nutrient sufficiency range for maize ear leaf sampled at the initial silking stage was 27.6 to 35, 2.5 to 5, 17.1 to 25, 2.1 to 10, 1.6 to 6, and 1.6 to 5 gm/kg for N, P, K, Ca, Mg, and S, respectively (Vitosh et al., 1981). Similarly, micronutrient sufficiency range for maize ear leaf was 20-150; 21-250; 4-25; 6- 20; 20-70, and 0.1-2 mg/kg for Mn, Fe, B, Cu, Zn, and Mo, respec- tively (Vitosh et al., 1981). Tyner (1946) observed the critical concentrations in maize leaves at silking to be 29, 2.9, and 13 gm/kg for N, P, and K, respectively. Results in Table 15 indi- cated that nitrogen concentration in the 1984 growing season was therefore below the critical N concentration (with few exceptions), further reducing maize grain yield. Besides nitrogen, nutrient concentrations of the maize plant were within the sufficiency range for normal maize growth and development. Judging from the concen- tration of maize leaf elements, it appeared that elemental nutrients were not a limiting factor for maize grain production. Nutrient uptake for both monocultural and intercrop maize were mostly not significant, indicating that the presence of bean 162 cultivars with varying densities in intercrop system did not impose any competitive pressure on maize growth and development and ulti- mately maize grain yield. Bean seed N concentration was between 41 and 49, while bean leaf N ranged from 40 to 57 gm/kg, indicating that nitrogen requirement for human nutrition would probably be adequate, par- ticularly in Tanzania where both bean seed and young fully expanded tender bean leaves are consumed. Furthermore, maize leaf N concen- tration was between 23 and 34 gm/kg, implying that animal nutrition might be improved by feeding sheep, goats, and cattle of the home- stead with bean and maize leftovers after grain harvest. Crop researchers should put more emphasis on the development of crop species with high nutritive values. These improved nutritive values would combat malnutrition in the third world. Nitrogen uptake for beans was about ten-fold the uptake of P and about three times the amount of K harvested from bean seed. 0n the other hand, maize N harvested from grain was two to three times higher than the uptake of P and K. Since associated culture is practised by low-resource farmers, it might be possible to increase yields simply by purchasing nitrogen fertilizer with their limited capital and applying it to their farms every year. CHAPTER 6 SUMMARY AND CONCLUSION Two cultivars of beans, Domino and Carioca, were evaluated at three densities in association with short season maize hybrid 422 at East Lansing, Michigan in the 1984 through 1986 growing seasons. Combination of experimental units included monocropping of the two bean cultivars and maize, and intercropping maize with three densi- ties of each bean cultivar, making a total of nine treatment combinations. Seed yield, biomass, relative light interception, pods, and leaf area index of bean in monoculture were significantly higher than the corresponding traits under maize-bean association. Pods/m2, leaf area index, and biomass increased with increasing bean plant density. Seed yield also increased numerically with increasing bean plant density although the difference was not sig- nificant. Seeds/pod and hundred seed weight were stable even under the less favourable growing conditions. The results indicated that maize shading and bean density did not affect the performance level of these two yield components. Seed yields of bean in associated culture ranged from 32 to 39 percent of the monocultural yield. Less favourable growing conditions in associated culture reduced leaf area index of Domino by 39 to 46 and Carioca by 23 to 37 percent. Highest bean LAI obtained from maize-Domino was 2.6 compared with the monocultural 163 164 value of 4.2, while the Carioca-maize combination produced the highest bean leaf area index of 3.3 with the Carioca monocultural value at 4.3. Optimum biomass production during the vegetative phase appeared to be a prerequisite for increased yield components. The relative light interception for the associated bean cultivars was between 43 and 53 percent of their monocultural light interception, resulting in reduced values of yield and yield- related components. Harvest index of bean in association did not reflect a predictable trend and ranged from 53 to 59 percent while HI of bean under monoculture ranged between 59 and 65 percent. Protein, N, P, and K yields of bean under monoculture during the first and third growing seasons were three-fold their asso- ciated culture yields. Seed yield of bean was significantly and positively correlated with seeds/pod, leaf area index, pods/m2, and biomass, positively, though not significantly, correlated with hundred seed weight. However, seed yield of bean was negatively though not significantly correlated with percent bean protein. Biomass was also negatively and significantly correlated with per- Icent bean protein. Furthermore, biomass was positively and sig- nificantly correlated with leaf area index, seeds/pod, and pods/m2. Biomass was positively though not significantly correlated with hundred seed weight. High carbohydrate concentration in the second growing season was associated with a limited sink, resulting from pod abortion due to moisture stress. Correlation analysis for three ‘seasons 165 indicated that bean seed yield was positively but not significantly correlated with root carbohydrate. Furthermore, non-significant correlation tests showed that stem and leaf carbohydrates were negatively correlated with bean seed yield, possibly due to increased pod number/plant (1984) which remobilized and depleted stored root and stem carbohydrates for seed filling, resulting in increased seed yield. Alternatively, pod abortion in 1985 (due to dry conditions) reduced pod number/plant, resulting in high accumu— lation of CHO in root and stem tissues and reduced seed yield. A constant supply of high rates of carbohydrates accompanied by high pod number per plant might result in large yield increases. Effects of years, bean cultivars, and bean density were not expressed for hundred maize kernel weight, indicating that maize was competitive and efficient in obtaining the essential resources for proper growth and development. Yields of maize under mono- culture were not significantly different from the yields of maize in association in the first and third growing seasons. The obser- vations indicated that each crop component reached a peak demand for resources at different times and from different soil profiles since the two crop species had different growth durations and morphology. Furthermore, the competitive ability of maize for under and above ground resources was higher than the bean cul- tivars. 0n the other hand, resources were adequate for the growth and development of the maize and bean cultivars in the first and third years. 166 Grain yields of maize were reduced by 15, 14, and 15 percent when maize was intercropped with Domino at 100,000, 150,000, and 200,000 bean plants/ha, respectively. The maize-Carioca combina- tions at 100,000, 150,000, and 200,000 plants/ha reduced grain yield of maize by 14, 13, and 15 percent, respectively, as compared with monoculture. The _efficiency of the two bean cultivars in combination with maize (40,000 plants/ha) peaked at 150,000 bean plants/ha, indicating that the combination might be superior to the other bean density combinations. Highest combined maize-bean yields were between 6,767 and 6,941 kg/ha while a half-hectare of each monocultural crop only produced a maximum combined yield of 4,718 kg/ha. The highest monocultural yield was 7,006 kg/ha. Even though grain yield of maize in monoculture was higher than any intercrop yield combination, the associated culture pattern would continue to be more important than monocrop maize because mixtures of maize-bean provided high protein yield needed for human diets in deve10ping countries. Combined maize-bean protein yield ranged from 810 to 870 kg/ha, while monocultural combined protein yield ranged from 671 to 681 kg/ha. The best monocultural protein yield (701 kg/ha) was always less than the combined intercrop protein yield. Maize and bean in associated culture combined total protein yield/ha was adequate to feed 34 to 37 adult males for one year, while protein yield/ha in monoculture was enough to feed only 28 to 29 men annually. Land equivalent ratio increased with increasing bean density. A land equivalent 167 ratio (three-year average) of 1.29 was obtained when maize was intercropped with Domino at 200,000 plants/ha. Protein, N, and P yields of maize in monoculture during the first and third cropping seasons were not significantly different from their corresponding yields in associated culture with few exceptions. Maize height was significantly and positively correlated with maize yield. However, kernel weight and land equivalent ratio were positively and not significantly correlated with maize grain yield. In contrast, bean biomass was significantly and negatively correlated, while bean seed yield was negatively but not significantly correlated with maize grain yield. Seed protein, N, P, Mg, B, Mo, and Zn concentrations of bean in association were not significantly different from the cor- responding monocultural values and their concentrations were within the nutrient sufficiency range for normal growth and development. Bean leaf protein, N, P, K, Ca, Mg, and Cu were not significantly different in the two cropping systems and their concentrations were sufficient for nOrmal growth and development. Calcium and Mg uptake of the 1984 and 1986 growing seasons was almost twice the amount absorbed during the 1985 cropping season, indicating that bean plants might show calcium and Mg deficiency during dry conditions which in turn could affect seed yield. Bean cultivars and densities did not affect grain protein, N, P, K, Ca, Mg, and the micronutrient concentrations of maize kernel. Since protein and nitrogen concentration of maize kernels in 168 association was not significantly different from the monocultural values, it seemed that nitrogen transfer from bean roots to maize roots did not take place in the associated maize crop. Macro and micronutrient concentrations remained constant throughout the experimental period, indicating that the effect of bean cultivars and density on the grain nutrient concentration of maize was not significant. Grain macro and micro-element concentrations of maize were sufficiently high throughout the experimental period and generally contributed to kernel filling and final grain yield. Bean cultivar and density did not affect leaf nitrogen, P, K, Ca, Mg, Cu, and Zn concentrations of maize since monocultural values were not significantly different from the results in associated culture. Besides nitrogen (1984), nutrient concentrations of the maize plant were within the nutrient sufficiency range for normal maize growth and kernel yield. Density combination of 40,000/ 150,000 plants/ha maize/bean, respectively, produced greater yield and could be recommended to farmers in Tanzania, although the success will greatly depend on local weather, soil fertility, general crop husbandry, and local cultivars grown in the country. Future Challenges In the literature search conducted by Francis (1986), there were 187 published papers up to 1960, but 359 papers were published from 1961 to 1970, and between 1970 to 1980 there were 1,440 published papers, showing that there is an increasing recognition by scientists and agricultural administrators of the current and 169 potential future importance of associated culture. The scientific community's role in attempting to increase yields from multiple cropping will be a continuous process since it is highly unlikely that farmers will adopt a monocropping system, due possibly to land, capital, and labour shortages. Family nutrition is very important for their livelihood and associated culture can improve the quality of the family's diet by providing high nutritive values of starch, protein, essential nutrients, and vitamins, in addition to those from fruits and vegetables. These high nutritive values can be obtained from a variety of crops grown in mixtures on a unit of land area. Mixed cropping will continue to be important in the develop- ing countries due mainly to population pressure and general poverty. Subsistence farmers lack capital for purchasing needed inputs like fertilizer. Thus intercropping cereals and legumes would possibly transfer (although evidence for transfer of N is not strong) some nitrogen to non-legume crops if legumes capable of fixing N in associated culture can be identified. Furthermore, these crop species differ in rooting patterns and can therefore exploit nutrients in different soil profiles. Mixed cropping, too, minimizes soil erosion due to early ground cover. In addition, some diseases and pests tend to avoid crops in mixtures and this is a bonus to a low-resource farmer in the third world. The inter- cropping system may use solar energy, nutrients, and water more efficiently than monocropping. Likewise, associated culture 170 reduces risks due mainly to increased diversity in crops. Such advantages of intercropping are some of the reasons why farmers in the tropics adopted this system of production and why they will continue to practice it as long as their land, labour, and capital problems are unsolved. Since the two bean cultivars planted at different densities did not show any significant yield differences, there is a need to continue with optimum bean density studies involving types I, II, III, and IV with preferred seed size, colour, and maturity in order to achieve high combined yields. Evaluating compatible crops with diverse maturity, optimum density, and diverse morphology will enable the compatible mixtures to explore a greater total soil volume and utilize light more efficiently than crop components with similar morphology. Each crop component will reach peak demand for resources at different times, thus minimizing competition and increasing yield potential of the cropping pattern. It is speculated that greater biomass will be produced in a mixture than in monoculture, thus resulting in greater demand on soil resources, mainly water and nutrients. Studies on mixtures of crop components capable of utilizing low levels of resources more efficiently will benefit low-resource farmers. Furthermore, studies on critical fertility levels in associated culture will provide an insight for improvement of the cropping pattern. Leaf and row orientation studies will have relevance to reduced crop competition for light at critical stages of development and 171 increase yield potential of the associated culture. Evaluating multilines of maize and bean cultivar mixtures with wide genetic diversity will probably minimize stress due to complexity of these associations. In addition, wide genetic diversity will reduce damage due to diseases, insects, and nematodes and maintain yield stability in bean-maize mixtures. Future challenges should also include the breeding of bean cultivar(s) which will tolerate and perform better under a complex associated culture system. Such a cultivar should be able to utilize available light more efficiently. It should tolerate shading environment under the associated culture. The cultivar should be capable of fixing nitrogen even under less favourable environmental conditions in order to increase bean seed yield and consequently combined total seed yield. Carbohydrate results revealed some doubts as to whether the bean roots and stems stored and translocated adequate amounts of carbohydrates to the reproduc- tive organs for seed filling. Therefore, the future challenge calls for screening of bean cultivars with high storage and trans- locatable root and stem TNC in order to increase seed yield in the two cropping patterns. However, these goals demand a greater degree of expertise in physiological, genetic, and breeding skills than encountered in national research centres in developing countries with the present outlook vis-a-vis personnel and finan- cial support. Nevertheless, a close collaboration with inter- national research centres would be a step in the right direction. APPENDICES APPENDIX A ANALYSES 0F VARIANCE .ee,e_ es. ege ee eeeueeeeaem ee=a_=.. .eesee me. use ea eeeueeeemem. e.¢e ~.ee m.m e.ee e.e s.e~ m.ee o.om es. >e eea.me non.ee~m ~en.e eee.s ~so.s gee..mm mmm.eee ~me.eem~ em taste see.me nee.eemm ene.e .mem.s .mss.s eom.mne «mm.~m .eme.mmee e seemees x se>_u_:u x see» -~.- ems.~mee mee.~ Nee.s ~os.s eon.meee Na~.eee ees.ee~ e seemeeo x toseeese see.ee mes.eene ~s~.s see.s nes.e Nee.see «ee.eee eee.saee e eeemees x some aee.ee ...es.eeoee Nee.e .eem.s ..ems.o ..m~e.esee ~a~.eee .eee.emmee N seemees -~.- ..-~.e~em~ ..mm~.ee ees.o mos.o emm.eaee .mee.~ee Nee.emme e ceseeeae x Lee, emm.m .mee.eeee~ ..s~m.oem eee.e ..ene.s ..eee.meeme ..m~e.smo~e Nes.mmmm e eeseeeae ..mee.eee ..-e.e¢e~me ..eem..e ..a~e.e ..¢es.e ..~.s.eeme~ ..mee.meee ..msm.e~seMe N Lee» as eeg\aee ease ease e26. e assae eoee eueoeee eeeee egmeez ee egaee eeem eeem geese seem ecu—a .6 .6 e>.»e_em uesussz ees< eesmem eessom came meseaam see: .esaepau ueeepuomm< es» s_ waves» ueee_em-u—e.> use u_e_> seem be euse_se> be mmmx_es< .es eeaeh muz<_¢<> mo mwm>eee eo. wee ea eeaoeseeoem seem_=.. .eesee mo. one on eeeossseosm. m.Me e.ee e.ee ~.ee eee >o smm.o mme.o mmm.se mme.m~m mm sossm mom.e emo.o mmm.m mmm.¢se N xesmsem x se>see=e x sees emo.o emo.o omm.me mmm.mms e xesmsem x se>seesm emo.e mmo.o esm.m mmm.msm N xesmsem x sees seemm.se es.mmm.e «emmm.mse t..mmo.ommm e xesmsem sess.m smem.o ess.mm «mmm.mmmm N se>sessu x sees seemm.s mme.o mmm.os mmm.m~me e se>sussu ssmse.sm «smmm.m tsmmmmmm tsmummdmmeee N see> Easemeeos mssossmoss semosesz sseuoss soueess sosuesse> seem seem seem seem so so eesmem eossom mesesom seez .essessu ueeesoomm< esp ss seem so uses» usessesz ueem so eosesse> so msmxses< .m< e—nes 175 ._e>e— do. esu ue “seessssmsm zpsasznn .—e>e_ mo. es» ue aseussssmsmc m.oe v.se “.me s.Me ¢.oe m.m_ ¢.me ~.ee s.m_ An. >9 eon. mom. moo. cso.m omm.e mos. sev.e son. mos. mm soggy men. com. mwo. s¢m.m mNm.~ sen—o.¢ neo-.~e «som~.m moo.~ N susmsem x se>su_:e x sees sen. eoe.e mmm. nnsmo.mo nmm~.oe «coo—.we amen.m «seem.o one. e aususes x se>se_:u ems. sen. mac. emm.m mom.e mnm.~ osm.~ mum. ~se.e ~ ausmsem x see» sm~e.~ .o~m.~ mes. nemo.o~ oe~.~ nssmm.m naewm.m~ snom~.v n.-m.m e susmses see. eme. mes. meo.m mv~.~ anum.~ cmm~.o com. nnu__.o ~ se>sa_su x see» omm. ems. one. emm.n NNm. mam. snmmo.om sum. nsmmo.o~ e se>_u—:u anomm.o nncvm.m mmo. c.vm~.mme namem.om nsmm~.m~ anvmm.no~ sam-.on na—mm.- u see» mas semom seseem uzs seasm soseum uzs semen suseum Ioueess sosuesse> seee seee seem seem . seam seam uoom eoom uoos so so eesmem eesaom eae\eae meseocm see: .essupsu ueeesoomm< ss ass—_ss uos-us: asssou sosuesuseosou eeesuAsoageu so ausmsem use .mse>su_=u seem .see» so auessu .v< e—aes 176 .easae eo. see ea eeeoeseeoem seemez.. .eesee mo. see ea eeeosseemem. N.m e.ee m.e N.Ne o.m o.m eee >o ooo.o eoo.o moo.o soo.o mme.o mmm.m mm sossm ooo.o eoo.o moo.o Noo.o NmN.o «No.ee N susmsem x se>sueau x sees ooo.o Noo.o Neo.o moo.o eeo.o mss.o e xesmsem x se>suesm ooo.o eoo.o Noo.o moo.o mmo.o mos.e N taesmsem x sees coo.o ooo.o Noo.o eoo.o coo.o sse.o e Ausmsem ooo.o ooo.o eeo.o moo.o sme.o Nmm.m N se>saeoe x sees ooo.o Noo.o «mmo.o eoo.o mN¢.o mom.me e se>su_=u esmoo.o temood «smo.o senso.o esm.o ems.se N sees Essmesmez Ease—em Easemeeos mssosomoss semosusz sseeoss Eoueesm sosuesse> Amx\5mv eewmem eowmom mesesom see: .esousou ueeesoomm< ese ss seem so sosuesuseosou usessuoz ueem so eosesse> so msmxses< .m< e—nes 177 .eesee eo. see em eeeosseem_m seemezss .eesee mo. wee ee eeeesseeoem. m.me e.m e.me o.m m.me m.N Axe >m smm.NN use.e mmN.o NNH.Nm Nms.N emm.o mm sossm mom.o emm.o ems.o mmm.sm mNe.o omN.N N mesmsem x se>susau x sees mmm.os smm.o Nms.o eNo.me oms.m m~m.o e xpsmsem x se>sessm msm.e sms.o mem.o mmm.e NNm.N mmm.o N hesmsem x sees mmo.oe omo.o smm.e eNo.e Nmo.o mmm.o e musmsem mmm.mN omN.e mmn.o omN.mm NmN.m «Nms.N N se>sessm x sees omN.om smm.e ONm.o htemmmgfim «ssms.sN «mmo.s e se>sussu eNm.Ne esmNN.Nm «essm.me «*mmm.meN nemsv.mm «stN.me N sees ossN emesemsez Easeuaasoz sose sesoou sosom soueess soseesse> Amx\mev eewmem eewmom mesesom see: .e.e.eeeoe ms eeeas .eesee eo. wee ee eeeoeseemem seeme=.. .ee>ee mo. wee ee eeeoessemsm. 178 o.m e.oN e.eN m.Ne m.Ne m.Ne eee >o mco.o Nmm.o NNN.o soo.o smm.o Nuo.me mm sossm moo.o mNo.o mee.o eoo.o mmm.o emo.me N musmsem x se>susou x see> Hoo.o moo.o mNe.o moo.o mmo.o meN.N e ausmsem x se>suszu meo.o Hoo.o cum.o Neo.o mmN.o mON.m N ausmsem x see» mNo.o eeN.o sme.o moo.o mNN.o mNN.oH e mesmsem moo.o ose.o sme.o Noo.o «smsm.m sesmN.ome N se>spsoo x sees moo.o mem.o sous.e smeo.o msN.o mme.om e se>sussm seeMN.e .seee.ee ..eNN.m ..eee.o somm.e .eae.Nm N see» Essmesmez Ease—em Easemeuos mososomoss semosusz sseeoss soueess sosuesse> Amx\emv eewmem eowmom mesesom see: .essusso ueuesoomm< esu ss seem so sosueseseosoo usessusz seem so eosesse> so msmxses< .m< e_nes 179 .eesee eo. wee ea eeeoeseeaem seemesss .ee>ee mo. use ee eeaosssemem. e.Ne N.NN m.e m.me N.eN N.Ne eNv >o eNm.mm Nm.Noe mNN.o Nae.eNee oom.oe mee.em mm Latte mem.ee omN.o omm.o Nem.NeoNe mem.e eme.N N seemems x taseeeao x tees eNo.Ne eee.Ne moN.e omN.oNNmm oee.o eNm.o e seemeeo x te>eee=o omN.mN omN.NmNe mee.o eNN.eoem NoN.me eNN.N N Neeaemo x tees eee.me eee.Neeme eNe.e mmm.o mmN.e eNo.oN e seemees omN.ee meo.eeee .seee.e eNo.eeeee eme.e .emm.moe N saseeeso x tee, .seee.Nmo Nm.NNeN .ste.ee mmm.mmmeme oee.o .seee.mem e saseeeso ..omN.eNe semeo.emeNe ..Nme.Ne eee.eNemeN .smm.eNN ..eee.mmmm N ease ossN emesemsez Esseunxsoz sose sesoou sosom Eoueess sosuesse> Amx\mev eewmem eowmom mesesom see: .e.e.eeeoe e< seems 180 .eesee eo. see ee eeeosseemem seemezs. .eesee mo. see ee eeeossseoem. e.e o.N N.N N.N eee >o Nms.smmemN moo.o emo.m NsN.mN em sossm mmm.mmee¢e moo.o mmm.m emss.mN s zesmsem x se>suesm x sees NmN.emN¢N eoo.o mme.m Nsm.om N sesmsem x se>sussu Nso.0NmONm eeo.o mNN.N «mNo.Nm s eafimsem x sees mNe.Nmsmm NNo.o mmN.N «seem.eem N musmsem NmN.Nosmom eNo.o ssm.N emm.me N se>seese x sees oom.emmee moo.o NNo.o Nsm.N e se>suszm seNmN.emmNNNem moo.o eom.m «sseo.osmme N sees Aes\mxv AEmV Aaov uses> osuem usmsez usmse: eoueese soseesse> ssesm use—e>s:om ueem eNsez so so usee uesusoz eesmem eossom meseaom see: .eteeeeo eaee_80mm< see es meeees eaeeees-eee_> use eeee> eNees so eeeeeee> so msmxeee< .Ns eeees .eesee eo. wee em eeeosseemem seemexss .eesee we. see ea eeeeeseemem. 181 m.e e.ee e.ee e.ee eNe >o mNN.e eeN.Ne eee.mNe oNe.mome NN geese eee.N eee.me meo.ee eme.oee N Neeaeao x se>eee=o x tees eNo.o eNm.o meo.N Neo.eee e seemees x easeeeeo eee.ee emm.NN omN.moN eee.NOee N Neeaeea x seas eNo.o eee.o omN.e ooo.NNe e seemees seee.eN eee.ee meo.eNe eee.eNee N Lesseeso x saws eee.me eNo.e NmN.mN omN.eeNe e Lesseeeo .semm.oee .seem.Nem .«mmN.NNme .smee.mmemNN N tees Easemeeos mosossmoss semosusz sseuoss Eoueess soseesse> eNsez eNsez eNsez eNsez so so eesmem eossom ee5\m3e mesesom see: .essu—su ueeesoomm< esp ss eNsez so usess usessusz ssesm so eosesse> so msmxses< .m< eeaes 182 .ee>ee eo. see ee eeeeeseemsa Neeoezss .se>e_ mo. esu we eseossssmsms m.m e.ee m.m m.s s.s s.s ANV >u ooo.o ooo.o Hoo.o Noo.o seo.o msm.o mm sossm eoo.o ooo.o ooo.o soo.o Noo.o smo.o N sesmsem x se>sus=m x sees ooo.o coo.o ooo.o coo.o ooo.o ooo.o e susesem x se>sus=u ooo.o ooo.o ooo.o Noo.o moo.o NNe.o N sesmsem x see> ooo.o ooo.o coo.o moo.o ooo.o Neo.o e musmsem coo.o ooo.o f.mood moo.o moo.o mse.o N se>ses=u x sees ooo.o oom.o Noo.o ooo.o moo.o Nem.o e se>sassu e«eNo.o sooo.o sseeo.o seame.o «sto.o ssmm~.m N see> Essmesmez Essosem Essmmeuos mssossmoss semosusz sseaoss soueess sosuesse> Amx\emm eewmem eowwom mesesom see: .esoussm ueueseomm< esp ss eNsez so soseesuseosou usesspsz ssesm so eosesse> so msmxses< .m< esoes 183 .eesee eo. wee ee eeaeeseeoem seemezss .ee>ee mo. one ea eeeeeseeosm. e.ee N.me N.me e.ee N.me e.ee ANV >m Hem.ee mem.o mNo.o ssm.m mms.o mme.o mm Lossm eNo.OH emm.o soo.o ess.me mmm.o omo.o N xesmsem x se>seesu x sees eNo.0N Noo.o moo.o mmo.s mme.o omo.o e ausmsem x se>sussm eNo.e Nmm.o moo.o ess.me smo.o omo.o N eSsmsem x sees eNo.o omo.o «No.o mmm.e somN.N ese.o e Ausmsem temmmms Nmm.o moo.o mom.NN scum.e sNo.o N se>sussm x sees eNo.o ooo.o ooo.o ooo.o smN.o mso.o e se>seszo semem.sse htestém mso.o tsmeudm mmN.o NeN.o N sees ossN emesemsez Esseunasoz sose sessou sosom soueess sosuesse> Amx\msv eewmem eowmom mesesom see: .e.o.eeooe as eeees 184 .eesee eo. see ee eeeoeseemea seemesss .ee>ee mo. use ee eeeoessemem. m.ee m.se m.Ne m.me m.oe m.eN ANV >0 emu.e soo.o moo.o Nee.o Noo.o Nsm.o mm gossm msm.N moo.o mNo.o Neo.o soo.o NmN.o N spsmsem x se>saesu x sees emmN.0e moo.o ooo.o moo.o eBod mme.o e assmsem x se>sessm sso.o ooo.o moo.o mmo.o Noo.o Nem.o N xusmsem x sees smsm.s eoo.o «mmo.o mmo.o moo.o osm.o e aesmsem mNm.e moo.o meo.o mNo.o ooo.o mNo.o N se>suszm x sees eoo.o moo.o eoo.o moN.o moo.m moo.o e se>suesu snsmm.se t3.365 «ssme.o seess.o nsmmo.o «Nmm.e N sees sosom Essmesmez Ease—em Easemeeos mssossmoss semosusz soueess sospesse> Amx\mev Amx\smv eewmem eowmom mesesom mesesom see: see: .essussm ueeesoomm< es» ss eNsez so soseesuseosom esessusz seem so eosesse> so msmxses< .o~< esses 185 .eesee eo. see em eeeoeseemem ee;m_1.. .eesee mo. see ee eeeosseeosm. m.ee m.ee m.ee m.m e.ee ANN >m NeN.mN ONm.N smm.o mNm.Nme mom.m mm Lossm mee.mm eNm.m mNN.o mmm.Nme msm.e N xesmsem x se>susom x see> mmm.mm eNo.us moo.o mmm.msm mmm.N e xesmsem x.se>se_:m mom.em mom.mm mme.o esN.om meN.m N musmsem x sees mmo.ss eNo.moe mom.o eNo.emm Nee.s e e3.3..sem eNo.s eNm.mm Nee.o mem.mm NNN.¢ N se>seesm x sees mmo.Nm tsSodom mNs.o mmm.sms NNm.m e se>sesou t..mmm.NNmN t.memmsmm «emmN.se semsm.Nst «seem.NNe N sees ossN emesemsez ssseunxsoz sose sesoou soueess sosuesse> Amx\mev eewmem eowmom mesesom see: .e.e.eeooe oes seems APPENDIX B CROP SCIENCE FIELD LAB RAINFALL DATA AT MICHIGAN STATE UNIVERSITY AGRONOMY FARM, EAST LANSING APPENDIX B CROP SCIENCE FIELD LAB RAINFALL DATA AT MICHIGAN STATE UNIVERSITY AGRONOMY FARM, EAST LANSING Total Inches of Rain per Month Year 1984 1985 1986 23-Year ‘ No. No. No. Average Month Total Days Total Days Total Days Rainfall April 3.59 14 4.28 10 2.89 12 3.21 May 5.42 16 2.44 8 3.56 12 2.96 June 0.19 4 2.29 7 8.91 12 4.04 July 1.93 8 2.19 9 2.49 10 2.87 August 3.72 6 4.29 13 3.84 6 3.07 September 3.54 14 3.22 8 9.56 15 3.27 October 3.80 11 5.02 10 2.84 11 2.15 TOTAL 22.19 73 23.73 65 34.09 78 21.57 Compiled by M.B. Tesar 186 APPENDIX C BEAN AND MAIZE SEED YIELDS 187 mNe.m oON.m emm.m omm.m ome.m omm.m moo.oe eNNeme eNsez Neo.e mNe mme eee mNo mee moo.ooe eoeeueo .m eNN.m Nem.e eNo.N Nmm.e eeN.e emo.N ooo.ooN emsseemooeeze ossEom .s moe.m mmm.m mmm.e Neo.e mNe.m NNm.m ooo.oe mNees NNe.e mNe oee ome eee . mNN moo.ooN oeeuom .m ome.m Nem.m mom.m Nem.m NNm.m Nmm.m oom.oe eNees NNe.e mNe mme ome meN emm oom.ome sesame .N mom.m mNm.m meN.m mem.m Nme.m emo.m moo.oe eNNe so mNeaz mmm NNm mmm mom mee emm ooo.ooe oeeuem .e eee\mev eeeem\5me >e eee ee e eae\emv meeeeeeeesoo see: see: musmsem usesueess sospeos—mem seem ss mussueem usess someem msszoso smme momms> mmmm mNHe eee ee e eeSNeme meeseaeeesoo see: see: musmsem useEpeess soseeosssem seem ss mmssueem usess .A.u.usoev someem msszoso smme 189 mme.m eeN.m mem.e NmN.m eme.e eee.e omm.oe mNeez Nee mmm mom mNm Nme mNe oom.ome aeoeuao .e eNm.e oNN.m emN.e Nem.e mmm.m mme.m oom.me eNNe em aNeez mme Nmm mmN eem Nee Nee omm.QOe aeoeuee .m Nem.e Nmm oem eeN emm.e mNe.e ooo.moN emsseesooeesm osssom .s mNm.m emm.m eNm.m Nme.m eNN.m moe.m oom.oe eNeez NNm mmm mem see New Nee ooo.ooN oeeuom .m mee.m Nme.m eoe.m eeN.e emN.e mee.e ooo.oe mNees mem eem mme mem emm eNm oom.ome oeemam .N emN.m eee.m mem.m mNm.e mom.e meo.m ooo.me eNNe mm mNeez NeN Nme ems eem eNm emm oom.oOe scenes .e ees\mem eeoem\5mm >e eee ee e eee\ems meeeeeeeeEOe see: see: xesmsem eseEueess soseeessqem seem ss mussueem usess someem msszoso mmme 190 mee.m mms.~ mom.m Neo.s mmm.N Nes.m coo.os Aessesoeosozs eNsez .m Nmm.e sem use Nmm moo.e emo.e ooo.ooN Aesop—soosozs eeossem .m mem.s smm.s oss.s mem.s ess.m eNe.m moo.os eNsez + mum Nmm NmN esm mss Nee coo.OON eeossee .N ees\mee eeoem\smv >e eee ee e ees\eme meeeeeeeeeee see: see: mesmsem useseeess soseeesssem seem ss mussueem usess .A.u.esoev someem msszosm mmme 191 mmN.N NNm.N mme.s Nme.m use.s omo.m oom.os eNsez Nmm mes mms mos eNs mmm moo.Ome eeosuee .m mmm.s Nmo.m msm.s ssm.s sem.m oms.m ooo.os ANNs :V eNsez com mmm osm st mom Nmm ooo.ome eeosuee .m ems.N ems.e mom.e mms.e mNs.e oos.e ooo.o0N Aessesseosozv ossaom .s meo.s mmm.m osN.N Nmm.m mNN.N msm.s ooo.os eNsez NNm ems mos mes oms oNs coo.OON ossuom .m mNo.N ssm.s mee.s meo.m mmo.m mem.s coo.os eNsez mmm mes mmm ems ass eNm moo.ome ossmom .N ems.N st.N mmo.s ems.s mmm.m NeN.m oom.os ANNs xv eNsez mNm ssm mNs Nmm NNm mem ooo.ooH ossmom .e eee\mem eeeem\Eme >e eee ee e ees\eme meoeeeeeeeee see: see: mesmsem eseEeeess soseeesssem seem ss mmssueem uses» someem msszosm mmme 192 mem.N eem.m mmm.m sem.m NNe.m Nsm.m ooo.oe Aesoesseosozv eNsez .m smm.N oms.e mmm.e NNe.e mmm.e esm.e moo.OON Aessesseosozv eeossem .m mes.s mem.s mmm.m mmm.m mso.s mmN.N ooo.os eNsez + mom oms mms omm mms use ooo.ooN eeossee .m ees\msm eeerNEmm >e eee ee e AesNeme meoeeeeeeeoe seez see: mesmsem useseeess soseeesssem seem ss mussueem usess .A.u.esoev someem msszosm mmme APPENDIX D BEAN AND MAIZE 100-SEED WEIGHT APPENDIX D 1984 Cropping Season BEAN AND MAIZE lOO-SEED WEIGHT Trait Readings in Each Replication Treatment Density Mean Combinations (pl/ha) I II III IV (gm) . Domino + 100,000 18.3 19.9 19.1 13.5 17.7 Maize (H 422) 40,000 29.0 28.3 30.4 32.2 30.0 . Domino + 150,000 17.6 18.3 18.6 18.0 18.1 Maize 40,000 30.0 35.9 32.4 34.5 33.2 . Domino + 200,000 18.7 17.1 18.8 17.9 18.1 Maize 40,000 32.3 31.3 38.4 31.5 33.4 . Domino (Monoculture) 200,000 19.9 18.5 19.2 18.9 19.1 . Carioca + 100,000 24.9 24.9 25.3 23.2 24.6 Maize (H 422) 40,000 32.9 31.1 33.8 34.2 33.0 . Carioca + 150,000 24.1 23.5 25.4 23.7 24.2 Maize 40,000 30.1 34.0 28.7 32.0 31.2 . Carioca + 200,000 23.1 24.9 24.0 23.5 23.9 Maize 40,000 33.2 28.2 32.4 31.7 31.4 . Carioca (Monoculture) 200,000 23.7 24.0 25.1 24.0 24.2 . Maize (Monoculture) 40,000 33.0 31.4 33.5 33.0‘ 32.7 193 _ 194 1985 Cropping Season Trait Readings in Each Replication Treatment Density Mean Combinations (pl/ha) I II III IV (gm) . Domino + 100,000 17.5 18.3 18.2 16.9 17.7 Maize (H 422) 40,000 35.3 31.1 29.6 32.8 32.2 . Domino + 150,000 17.2 17.9 19.2 16.9 17.8 Maize 40,000 40.2 30.9 29.1 37.1 34.3 . Domino + 200,000 19.0 17.8 18.0 17.2 18.0 Maize 40,000 31.7 30.9 31.3 31.5 31.3 . Domino (Monoculture) 200,000 18.9 18.7 17.0 16.6 17.8 . Carioca + 100,000 22.2 23.0 22.1 18.6 21.5 Maize (H 422) 40,000 37.5 31.4 28.9 30.9 32.2 . Carioca + 150,000 21.5 21.7 19.8 18.5 20.4 Maize 40,000 34.5 33.4 29.4 30.6 32.0 . Carioca + 200,000 21.8 23.5 18.1 17.3 20.2 Maize 40,000 37.6 31.6 31.4 29.6 32.5 . Carioca (Monoculture) 200,000 22.8 22.8 22.1 20.0 21.9 . Maize (Monoculture) 40,000 37.6 33.8 31.6 34.4 34.3 195 1986 Cropping Season Trait Readings in Each Replication Treatment Density Mean Combinations (pl/ha) I II III IV (gm) . Domino + 100,000 20.2 20.4 20.5 19.7 20.2 Maize (H 422) 40,000 32.8 32.6 32.4 29.6 31.8 . Domino + 150,000 20.1 20.1 21.2 19.8 20.3 Maize 40,000 30.3 30.7 33.3 31.0 31.3 . Domino + 200,000 20.4 19.6 20.4 20.7 20.3 Maize 40,000 31.2 31.0 28.6 29.1 30.0 . Domino (Monoculture) 200,000 22.1 18.5 19.0 19.6 19.8 . Carioca + 100,000 25.7 25.0 25.8 23.9 25.1 Maize (H 422) 40,000 31.6 33.1 31.2 31.5 31.8 . Carioca + 150,000 24.8 25.7 24.4 25.0 25.0 Maize 40,000 34.7 30.4 32.6 29.9 31.9 . Carioca + 200,000 24.5 23.2 24.8 24.8 24.3 Maize 40,000 30.3 29.9 33.6 33.8 31.9 . Carioca (Monoculture) 200,000 23.2 24.3 24.9 24.7 24.3 . Maize (Monoculture) 40,000 37.6 33.2 32.3 33.3 34.1 APPENDIX E BIOLOGICAL (BIOMASS) YIELD (gm/m2) APPENDIX E BIOLOGICAL (BIOMASS) YIELD (gm/m2) Trait Readings in Each Replication Treatment Mean Combinations Year I II III IV (gm/m2) 1. Domino 1984 184.6 269.9 243.6 231.6 232 + 1985 169.4 181.8 92.6 121.6 141 Maize (H 422) 1986 99.8 60.4 144.2 77.0 95 2. Domino 1984 222.1 291.3 166.1 443.2 281 + 1985 201.4 151.9 124.8 223.1 175 Maize 1986 43.9 95.8 104.1 113.4 89 3. Domino 1984 151.2 202.4 227.2 302.4 221 + 1985 266.8 195.6 166.4 227.6 214 Maize 1986 62.4 75.2 226.4 173.2 134 4. Domino 1984 382.0 690.4 665.2 810.4 551 (Monoculture) 1985 369.6 332.4 278.0 369.2 337 1986 331.6 348.4 247.1 380.4 327 5. Carioca 1984 220.0 192.0 211.0 215.4 210 + 1985 141.2 71.8 63.0 113.2 97 Maize (H 422) 1986 82.0 93.6 135.4 74.0 96 6. Carioca 1984 254.9 209.2 219.1 230.8 228 + 1985 204.2 151.1 130.2 113.2 150 Maize 1986 93.4 111.6 146.3 101.5 113 7. Carioca 1984 280.0 391.2 252.0 310.8 308 + 1985 157.6 217.6 126.8 94.4 149 Maize 1986 87.6 66.0 83.2 72.8 77 8. Carioca 1984 615.8 617.6 508.4 673.2 604 (Monoculture) 1985 357.2 263.2 268.4 157.6 262 1986 282.0 432.0 308.0 332.8 339 Note: Treatments 1 and 5 (100,000 bean pl/ha); 2 and 6 (150,000 pl/ha); 3, 4, 7, and 8 (200,000 bean pl/ha). 196 APPENDIX F MAIZE-BEAN LAND EQUIVALENT RATIOS (LER) APPENDIX F MAIZE-BEAN LAND EQUIVALENT RATIOS (LER) Trait Readings in Each Replication Treatment Combinations Year I II III IV Mean 1. Domino 1984 1.14 1.29 1.17 1.16 1.19 + 1985 1.22 1.38 1.15 1.12 1.22 Maize (H 422) 1986 1.15 1.28 1.12 1.25 1.20 2. Domino 1984 1.30 1.38 1.24 1.23 1.29 + 1985 1.43 1.31 1.14 1.40 1.32 Maize 1986 1.03 1.20 1.24 1.22 1.17 3. Domino 1984 1.37 1.23 1.27 1.27 1.28 + 1985 1.40 1.27 '1.36 1.35 1.35 Maize 1986 1.12 1.21 1.20 1.39 1.23 4. Carioca 1984 1.22 1.21 1.21 1.20 1.21 + 1985 1.27 1.21 1.15 1.19 1.20 Maize (H 422) 1986 1.27 1.27 1.08 1.28 1.22 5. Carioca 1984 1.14 1.32 1.29 1.15 1.22 + 1985 1.35 1.31 1.22 1.23 1.28 Maize 1986 1.20 1.15 1.21 1.26 1.20 6. Carioca 1984 1.52 1.32 1.18 1.21 1.31 + 1985 1.24 1.17 1.13 1.08 1.15 Maize 1986 1.23 1.17 1.38 1.28 1.28 7. Maize/Bean 1984- Monoculture 1986 1.00 1.00 1.00 1.00 1.00 Note: 1 and 4 (100,000 bean pl/ha) 2 and 5 (150,000 bean pl/ha) 3 and 6 (200,000 bean pl/ha) 197 APPENDIX G BEAN LEAF NUTRIENT CONCENTRATION mm mNe om.ee ems N.Oe mm m.Ne «.mm m.me s.s e.ss s.smN OON eeosseu .osoz N me use ON.HH msm m.ee mm m.Ne s.mm m.se o.s m.ms «.mom coN ossEom .osoz N ms mm om.ee smm m.ee mm s.Ne m.Nm e.ee N.u m.ms e.mom CON N me see cm.ee mmm s.m mm m.me o.Nm N.Ne N.m e.m¢ m.oom see eeossem N as es om.oH omm e.ee mm s.Ne m.mm e.ee m.m o.sm N.emN OON N as mse oo.ee mos e.ee mm m.Ne m.mm e.ee m.m «.mm N.m0N ooe osseom N mm one oo.Ne mum «.me mm e.ee «.ms e.ee m.e e.ee m.mNN eeN eeosseu .osoz e ow see om.oH mom N.Oe mm s.Ne s.sm e.ee e.s s.ms s.som eeN osseom .osoz e em em os.ee mmm e.me mm N.Ne e.ee e.ee e.s e.ee e.mmN eeN H mm Nme cm.Ne ssm o.me es m.ee m.ss m.me m.s e.Ns e.mmN ace eeossem e Ne ms os.ee mmm e.ee em e.ee s.mm e.me m.m m.ms s.mmN eeN H mm mme ce.ee ems m.m em ¢.Ne m.mm e.me m.m s.Ns o.mmN ome osssom e sN :2 oz em so m a: em x s z sseeoss Aes\so moss meesse> soseeesssem mesmsem ms\me mm\sm someem mssssosm smme zosh soseeesssem mesmsem ms\ms .ms\am A.u.esoev someem msssoose smme 200 CH.N mmm «.mH um N.N C.CH N.NN C.m N.ms C.mCN CON eeosseu .osoz N NH.C sue m.mH mm H.N N.mH C.CH u.¢ m.m¢ H.mmN CON ossEoC .osoz N mu.C eNm N.mH mm H.m m.NH N.CH m.v H.Hm ¢.CHm CCN N CN.N mmm C.wH Ce m.N m.CN C.CN ¢.m C.Nv m.NCN CCH eeosseO N NN.C HON C.NH mm C.N C.sH C.CH ¢.u C.Nu N.mCm CCN N CC.C CsN m.mH mm C.C C.NH N.¢N w.¢ C.Cm m.NuN CCH ossEoO N mC.m mos m.NH ON H.N N.HH H.CH m.¢ m.N¢ C.CCN CON eeosseu .osoz H mC.C HON C.NH Nm m.N m.NH u.uH m.¢ C.Nu ¢.CCN CCN osHEoO .osoz H CN.C Nmm w.HH mm m.s N.NH C.CH u.u m.Nm H.mmm CON H mm.m mHm C.¢N ms m.s C.CH C.mm H.N C.CC C.msm OCH eeosseu H CC.m mum u.mH mm ¢.N «.mH m.NH m.¢ N.Cm e.CNN CON H CC.m HHm «.mH mm m.C H.HH N.CH v.¢ C.Nm C.mmN CCH ossEoO H as me me m m: me e m z eeoeosm ees\es eoee memese> eoeeeoeemos mesmsem .CM\OE ms\am someem Cssssosu mmOH 201 em mm Nm.e NNm e.oN em N.e N.NN e.mN e.ee o.mNN ooN eooeseo .oeos e me mN mm.N oNe m.oN Nm m.e N.NN N.Nm N.mm e.eeN ooN oeesom .oeoz e me mm em.m ems m.oN me N. e.eN m.mm N.ee m.NmN ooN e em mm ee.N ems m.oN em N.e e.eN e.ee e.ee o.mmm ooe eooeeeo e Ne em mN.e mom e.NN oe e.e e.mN N.mN m.om e.mme ooN e Ne em eN.N mNm o.mN mm m.e m.NN N.eN e.em m.NNN ooe cessam e me mN me.N eem m.Ne mm m.N N.me N.mN N.me e.emN ooN mooesee .oeos m Ne Nm mm.N emm e.ee Nm N.N m.oN N.mN m.NN m.Nee ooN oeesem .oeos m es mm ee.N emN e.ee Nm N.N e.ee e.eN e.ee N.mem ooN m Ne em me.N Nmm m.ee Nm N.N e.ee N.NN e.ee m.NNN ooe aoeesee m ee Nm me.N mNm m.me mm N.N m.NN e.me e.ee m.NNN ooN m me mm eN.e Nmm e.mN Ne e.e e.NN N.mN e.ee N.emN ooe cessam m eN e: as as me m m: me e z eeoeosm ees\em moev meosse> eoeeeoeemmm mesmseC OM\CE Cx\sm, H.u.esoev someem Cssososm mmCH 202 HC mm OC.CH HOm O.NH NC C.O N.CC C.CN N.C C.Os N.CCm CCN eeosseu .osoz N NN NNH CN.O Csm C.NH CC O.m O.Ns C.Cm N.m H.CC s.ssm CON ossEoO .osoz N mC OHH CN.CH COC C.CH OC N.C O.Hm C.CC H.s m.Oe N.HHm CCN N HC NNH CC.NH NCC N.CH Hm O.N C.CC s.Hm C.C C.CN C.CeN OCH eeosseO N CC CNH CC.O NOC H.CH CC C.m C.CN m.mN m.C H.sC H.mmm CCN N Ne CmH CN.CH Csm C.CN OC m.m H.sC C.CN C.C C.Os C.CHm CCH osHEoO N me «C CN.CH CNN C.NH HC O.m H.ON H.NN C.C N.me H.CON OCN eeosseC .osoz H CC CC Ns.O HOH N.CH HC ¢.O «.mm N.HN N.C N.NC O.HOm CCN ossEoC .osoz H CC mHH CN.HH CNC C.CH NC N.HH C.Nm e.OH N.C C.s¢ N.CNN OCN CC eNH CH.HH OOs H.CH NC N.O N.Cm C.CN C.C H.Cs C.CCN OCH eeosseC H CC HsH mN.O mms O.CH mC s.m C.CN C.¢N N.C m.NC m.NOm CON H NC NCH ss.O Csm H.OH sC N.C m.mm C.CN C.C C.sC N.Hsm OOH ossEoO H sN :2 oz em 3C m Oz eC x s z sseeoss Hes\Hs mCHv >.ee.£e> soseeessoem mesmseC YOs\OE Ox\sm someem Ossssose CmOH 203 Cs HC CC.HH NNN C.NH NC 0.0 N.Cm N.CN N.C N.CC O.CHm CON eeosseC .osoz s we CCH CC.O NHN O.NH Ne O.CH H.Cm N.CH N.C s.sC C.Csm CON ossEoO .osoz s NC sO CC.mH sCs s.NH NC m. H.Cm C.CN O. N.CC O.Hsm OCN s CC HCH CN.sH CON N.CH OC C.N H.CN H.HN N.C C.Om N.msN CCH eeosseC e Hs NN N0.0 mmN N.mH HC N.HH C.CN C.NH C. C.Ce C.CmN CON s Nm Cm NN.O CNN C.HH vs C.O C.NN m.sH m.e N.OC C.ONm OCH ossEoO s NC NC CC.HH msm C.sH HC C.CH N.mC N.mN O.C C.CC s.sHm CCN eeosseO .osoz m Cs mN CC.O CNH N.HH Cs N.CH C.Nm C.CH H.C H.CC C.CCC CON osseoC .osoz m CC CNH OO.HH mmC C.NH mN H.CH C.NC C.CN m.C C.CC N.Hmm CON m OC HCH CO.NH mNs N.CH NN C.O C.CC H.Cm N.C N.HC H.CNm CCH eeosseO m HC Cm CN.CH mmm N.mH CC C.O C.Os C.NN N.C s.sC C.Osm CON m CC CHH CC.O OHm O.CH NC C.O H.Cm C.NH N.C C.NC C.NNm OCH ossEoO m sN :2. oz em :C m C: eC x s z sseeoss HesNHs mCHv Neesse> sosueesHsem mesmseO OJNOE ONNEO A.u.esoev someeC Ossososu CmOH APPENDIX H MAIZE LEAF NUTRIENT CONCENTRATION sC Nm OC.C smH H.CH N.CH C.C H.N C.OH e.s H.CN Ce eNsez .osoz N HC Cs OC.C CNH C.CH C.CH N.C N.C C.HN C.C C.CN CON N «C CC Cm.C CeH C.CH C.HH C.C s.N C.¢N C.C C.CN CCH eeosseu N CC Hs Ns.s CNH N.mH O.CH C.C C.C N.CN N.C C.HN CON N mC ms NC.C mmH s.CH N.HH C.C H.C N.NN C.s H.CH OCH ossEoO N CN mC OC.C mCH C.CH m.NH N.C C.C C.CN C.C C.CN Cs eNsez .osoz H NC Cm CC.¢ CHH C.CH H.HH N.C O.C H.CN O.m C.CN CCN H NC Om CN.s HmH O.CH N.CH O.s m.N C.CN C.C C.CH OCH eeosseC H OC mu Os.s CsH H.CH C.CH C.C C.C C.NN s.¢ C.Cm CON H NC Cm CO.s CmH C.CH N.sH C.C N.N O.CH C.C C.CN OCH ossEoO H sN s: o: em 3C m Oz eC x s z HesNHs mCHO sesz soseeesHsem Nesmsem uessoseseesH .Os\OE .OsNEO eNsez someem OssososO smOH zCHN soseeesHses NesmsmO 33... Sea H.u.esoeC someeC OsszosC CCOH 212! em eC.m ee.m mm oo.ee Cm.m m.e m.Ne o.Nm o.mmN ooN Comesee .oeoz N mm Ne.m em.C mN om.Ne oN.m o.N C.me e.CC C.CNN ooN oeseom .oeos N mm CN.e NC.m mm om.oe me.e o.N C.Ne C.NC m.NmN ooN N mN mm.m om.m Nm om.ee mo.m N.N m.me m.mm C.mCN ooe Cooeeee N om oe.ee CC.C so oo.me em.m m.e m.ee C.mC N.Coe ooN N Nm om.oe NN.m Co oC.Ne CC.m N.e C.Ce e.mC C.moN ooe oeeeom N em NC.C NN.C me oe.Ne oe.oe o.N m.me N.NC N.CCN ooN eoeesae .oeo: om mN.e CN.C eo om.me oe.oe o.e C.Ne C.NC N.CCN ooN oeesem .oeos Nm eo.e oe.C me oN.ee em.m o.N m.me m.NC m.NeN ooN mm em.e ee.C NN om.Ne CC.m C.N m.Ne C.mC m.emN ooe Nosesae mm mm.m me.n mo oC.Ce CC.m e.e N.Ce e.eC m.mmN ooN Nm NC.m NC.C eN om.Ce om.oe e.e o.Ce o.NC N.CCN ooe oe.som e: o: 8 3 m ms me e. N z 539:. semi o: 32...; 558.33. eeme m -Oxwua. Ossmu someeC Osszosm CCOH 2213 em oN.oe NC.C NC oe.Ne CC.N e.Ce N.Nm C.mNm ooN coasteo .oeax C on mm.m oe.C mN oe.Ce om.oe m.Ce m.mC e.eom ooN oeeeom .oees C oC oe.ee em.o eN oe.Ce oo.m m.me e.em N.mNN omN C mC oC.Ne me.e eN oN.me oN.oe e.ee o.Cm m.NeN oee Coaesee C en oC.oe oe.C mN oN.Ce CC.C C.Ce e.eC N.emN ooN C me oC.m mN.C me oC.Ce me.m e.Ce o.mC o.ooN ooe oeeeom C me NN.C mN.C mm oe.ee ee.m e.Ne e.eC o.oeN oCN Coeesee .oeos CC om.oe eo.m No oC.Ne em.m e.ee N.CC m.eNN ooN eeeaom .aeos Cm oC.Ne mo.N NN oC.Ce me.m C.Ce e.nm m.eem ooN N mm oe.oe CC.N oo oe.ee NC.m N.Ce m.Cm e.mCm ooe Coastae N Nm oe.oe CC.N Ne om.Ce CC.C e.Ce o.NC m.NeN ooN N me CN.m CN.C mN oC.Ce NC.m N.me e.eC o.ooe ooe eeeeom m e: as me so m m: CC C N z eeoeosm ACMNNN oeC NemesCC eoeeeoeeeom C.CC e ms\me messm C.C.Ceeos Comeom message meme 2111 mN oe.oe _e.C em CC.N oe.oe N.N e.N e.ee C.C e.eC N.eeN ooN Coastee .oeez N CN oN.Ne oC.N Ce oC.oe Co.m o.N m.e C.Ne C.C m.oC C.CCN ooN oeeesm .oeos N eC oN.Ne om.N No CC.N om.ee o.N C.e m.Ne m.C e.eC m.oeN ooN N NC om.Ne CC.N Co mN.N oo.ee e.N C.e e.Ne C.C o.oC o.omN ooe Cooesse N CC om.Ce CC.N Co em.m oC.ee e.N C.e C.Ce C.C C.CC N.CoC ooN N CC oN.Ce Ne.N Ne oC.ee om.Ne e.N o.e C.Ce C.C C.NC m.mmN ooe oCCECm N mN oC.Ce mN.C NC Cm.N CN.m e.N C.N C.ee C.C C.CC N.mNN moN Cooesae .oeaz e oC oe.Ne No.N Ce oe.m CC.m o.N e.e m.Ne C.C o.NC N.CCN ooN oeesom .oeos e CC oC.ee CC.C Ne Nm.m oN.oe N.N C.e N.Ne e.C C.CC o.oeN ooN e NC oC.Ne mm.e Co oC.m om.oe o.N N.e C.Ne e.C N.CC C.CCN ooe Cooeseo e mN om.Ne No.N CN Cm.m oC.oe C.N N.e C.Ce C.C o.CC o.mNN ooN e CC om.Ce CC.N NN oC.Ce oN.Ne N.N N.e C.me C.C o.NC N.CmN ooe assess e CN s: o: as so m m: Ce C s z eeeeoss AeuNes oee Neoetes eeeeeoeesos C.CC m mCNOm msxem someeC Osszose CCOH 2155 oC oC.oe me.C om Ce.N NC.C C.N o.N N.Ne o.C C.oC C.NCN ooN Coo_seo .seos C CC oo.ee oe.C NN mo.m mm.m C.N o.e C.Ne N.C m.oC C.omN ooN eeeeom .oeos C NC om.ee CC.C eN NC.N oN.ee C.N o.N o.Ce C.C C.CC N.CCN ooN C NC oN.ee NC.C mo NC.N oC.ee N.N N.e e.Ne N.C C.oC N.emN ooe CooetCo C CC oN.Ne om.e Ne NC.m oN.oe C.N N.e m.Ce N.C C.mC o.CeC soN C CC oC.Ne CC.C CN oC.e oC.oe N.N o.e C.Ce o.C N.Ce o.CCC ooe oeeeos C mN oC.ee eo.C CC CC.N CC.C N.N m.e e.Ne e.C C.NC C.CCN ooN Cooeseo .sesz C eC om.ee Ce.C Co oC.Ce oo.ee C.N m.e m.Ne o.C C.NC N.CmN ooN assess .Ceos C CC om.Ne Ce.C No om.e oo.Ce o.N C.e C.Ne C.C C.CC e.CNN ooN C CC oN.Ce mC.C NN NN.C oC.Ne N.N C.e m.Ne m.C C.CC e.CeN ooe Coe_teo C CC oo.Ce oe.C CN oo.oe oC.oe C.N C.e o.Ce o.C C.CC N.CoC ooN C CC oC.Ne CC.C mN om.oe oo.oe N.N C.e C.Ce C.C C.NC C.mmN ooe eeeeos C CN s: o: as so m C: Co x s z eeeooss ACuNes oeC CoseeCs eseosoeeses C.C: s ms\me messm H.C.oeoos someem Ceesoso oCCe APPENDIX J MAIZE SEED NUTRIENT CONCENTRATION CC NN.N NH. NC OC.C OH.N C.N N.C C.C N.C C.CH C.CO CC eNHez .osoz N CC NC.N HC. CC CH.C OC.N C.N N.C C.C C.C H.CH C.CO CON N OC HC.C ON. NC NO.C HC.N N.N N.C H.C C.C C.CH N.CO CCH eeosseC N CC CC.N CC. HC HC.C OC.N N.N N.C H.C C.C C.CH N.CO CON N CC CN.N CN. CN CC.C ON.N C.N N.C O.C N.C N.CH O.HO CCH ossEoO N HC CN.C CN. CC CC.C CC.N C.N N.C N.C C.C C.CH N.CO CC eNCez .osoz H CC CC.N CH. CC CC.C CC.N C.N N.C C.C. C.C N.CH H.CO CON H CC CN.C NC. HC NN.C CC.N C.N H.C H.C C.C O.CH O.CC CCH eeosseC H HC NC.C CN. CN CN.C CC.N C.N N.C N.C C.C C.CH C.OCH CON H HC CN.C CN. CN NH.C NC.N H.N N.C C.C N.C O.CH H.CO CCH ossEoO H sN s: o: em :C m Oz eC x O z sseeoss HesNHo CCHV sesz soseeesHoem CesmseC ueoooseseesH eesez OsNOE OsNEO someem Osssoosu onNzomm_e_=e =o_eeu__qem seem seem seem seem seem seem poem eooa poem Cusmcea :eeC OxNEO H.C.ucoev comeem Ocsqqogu CCOH 224 CC NC CN NCH HNH CC NCH CC CC CCN euo_LeC .osoz N CC HC CN NNH NHH CC CNH CC OC CCN ecsEOC .osoz N CC CC CN HCN CNH CN CCH HC NN CCN N CC CC CN CCH CCH HC CC NC CC CCH euosgeC N NC NC CN CCH CHH NC NCH CC CC CCN N NC CC CN CCH OHH CC CCH HN CO CCH ocsEOC N CC CC CN HCH CNH NC OCH NC NC CCN euosLeC .ocoz H CN OC CN NHN HCH HC CNH NC CCH CCN ocsaoo .ocoz H NC CC CN NNN CCH HO NCH HC CC CCN H HC CC CN NCH NHH CC HN CC CN CCH euosgeC H CC CN NN CCH CC CC CHH CC CC CCN H NC CC NN COH HNH NN CCH CC . CN CCH ossEoC H ezs Lease gugepm ezs Lemam gugeem ezs gemam gugeem Ae=\_a eoHC Le>se_=e =o_eeu__nee seem seem seem seem seem seem poem poem uoom Casmceo :eem : OxNEO comeem Ocseeogo CCOH 225 NC CC CN CCH CO CC OCH CC HC CCN euosgeC .ocoz C OC CC CN CCN CHH HO NCH OC CN CCN ocssoo .ocoz C NN NC CN CCH CO NC CHH NC CC CCN C CC CC CN NCH NHH CC CC CC CC CCH euosLeC C CC HC NN CCH CHH CC NCH CC NC CCN C CC CC CN HCH HCH CC NCH CC CC CCH ogsEOC C CC CC CN NCH CHH CN CHH CC CC CCN euosLeC .ocoz C OC CC CN CCH CO CC CCH CC CC CCN o:_EoC .ocoz C NN NC CN CCN OCH CO CHH CC NC CCN C NN CC ON CCH OC CC OC CC CC CCH euosgeC C CC OC CN NCH CCH HC CNH OC ON CCN C HC OC NN CCH CO CC NNH CC HN CCH oesEoC C ezs Leeam :ueeem ezs eemzm gugeem ezs Lemam gugeem Ae;\_g eoHC Le>se_=e =o_eeu__qem seem seem seem seam seem seem uoom uoom poem Cusmceo :eeC OxNEO H.C.ucoev comeem mcsaaogo CCOH 226 CC CC HN NO NC CC NC CN HC CCN eoosgeu .osoz N CC CC CN CO NC OC CC CC CC CCN ecsEoC .ocoz N CN CC CN NCH CC CC CN NN CC CCN N HC ON NN CO CC CC CN NN CC CCH euoPLeC N CN NC CN CCH CO CC NO CC CC CCN N CC CC HN NCH HCH HC CC HC CC CCH oesEeC N HN HC CC HNH ON NC CN CC CC CCN euosgeu .ocoz H CC CC CN HCH CC CC CC NC CC CCN ecsEoC .ocoz H CN CC CN HCH CO CC CN HC CC CCN H CC CC CN CCH CN HC CC CN NC CCH euesLeC H NC CC HN NCH NO CC NC NC CC CCN H NC NC CN HO HC CC CC NN HC CCH ecsEoC H ezp Lease geeepm ozp geezm :ueepm ozp eemzm gugepm me;\_e eeHC ge>sppzo coppeuwpeem seem seem seem sepm eepm Eepm poem poem poem Cpsmeeo :eeC OmNEO :omeem Oeseoegu CCOH 227 NC CN CN NCH CCH CC CC CN CC CCN eoosgeu .ecoz C CC ON CN NNH CC OC NN CC CC CCN o:_EoC .osoz C CC HC NN CNH NO NC CC CC CC CCN C CC NC CC CNH CO CC CC CN NN CCH eoesLeC C CC NC HN CCH NO CC ON NC NC CCN C CC HC CN CNH CC NC OC CC CC CCH oesEoC C CC CC CN CCH NN CN CC CC CC CCN euopgeu .osoz C CC CN ON CHH CN CC CC OC HC CCN oesEoC .ocoz C CC NC NN OO CC HC CC HC NN CCN C CC NN NN HC NC CN CC CH CN CCH euosLeC C HC CC HC CO CC HC NC NN CC CCN C CC ON CN NC NC CC OC CN ON CCH ecsEoC C ezp geeam gugepm ozp geese gueepm ezp geese :egepm Ae;\_e mofiv ee>_p_=o =o_peu_pqem seem seem seem Eepm sepm Eepm poem poem poem CpsmoeC eeem \Om\EO H.C.peoov oomeem OesooeLC CCOH APPENDIX L GLUCOSE STANDARD SOLUTIONS APPENDIX L GLUCOSE STANDARD SOLUTIONS Stock Standard Distilled Water Fina] Sugar Concentration O H omoouoam-bwmrp m1 m1 m1 m1 ml m1 m1 m1 m1 m1 m1 CCCCCCCCCCO O O O O O I I O O O I Nw-p-moxwookoo a a—l m1 m1 m1 0 mg/L 10 mg/L 20 mg/L 30 mg/L 40 mg/L 50 mg/L 60 mg/L 70 mg/L 80 mg/L 90 mg/L 100 mg/L 228 APPENDIX M STARCH STANDARD SOLUTIONS APPENDIX M STARCH STANDARD SOLUTIONS Final Stock Standard Distilled Water Starch Concentration 0 ml 4.0 ml 0 mg/L .1 ml 3.9 ml 10 mg/L .2 ml 3.8 ml 20 mg/L .3 ml 3.7 ml 30 mg/L .4 ml 3.6 ml 40 mg/L .5 ml 3.5 ml 50 mg/L .6 ml 3.4 ml 60 mg/L .7 ml 3.3 ml 70 mg/L .8 ml 3.2 ml 80 mg/L .9 ml 3.1 ml 90 mg/L 1.0 ml 3.0 ml 100 mg/L 229 APPENDIX N STANDARD CURVE FOR CARBOHYDRATE ANALYSIS CNCOOO. u N; HcospeHegLoC "x eNNCO.CCH e NCHCCCH. u > ”cowpeecm CCCO. Hazy eoeeeeomeC CHCHH pope mo_=e CHC>m1CCmmCC Cm