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E. Nidders Major professor Date August 9, 1988 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES » RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. m 9- 12, “"2 319%. n 170'“; “031676”?! THE INFLUENCE OF NITROGEN AND PHOSPHORUS NUTRITION 0N TOMATO TRANSPLANT ESTABLISHMENT by Ronald N. Barton A THESIS Submitted to: Michigan State University in partial fulfill-ant of the requirements for the degree of MASTER OF SCIENCE Department of Horticulture 1988 5/ 77753 ABSTRACT THE INFLUENCE OF NITROGEN AND PHOSPHORUS NUTRITION ON TOMATO TRANSPLANT ESTABLISHMENT By Ronald W. Garton Studies were conducted to evaluate the importance of nitrogen (N) and phosphorus (P) nutrition during transplant production, on establishment and yield of processing tomato seedlings grown in 288 cell plug trays. Transplants which were treated with a relatively high fertility regime (150 ppm N, 64 ppm P and 125 ppm K) during greenhouse culture, produced lower fruit yields than plants grown with a 75 N, 32 P and 62 K treatment. Withholding fertilizer prior to transplanting reduced tissue nutrient concentration, and plant growth after field setting and resulted in lower fruit yields. High N (280 ppm) pretransplant treatments resulted in reduced plant stands in early season plantings. High P (155 ppm) treatment concentrations improved plant surviveability following transplanting and resulted in higher marketable yields for the early planting date. Fertilization treatments did not affect growth, stand or yield in a late-season planting. ACKNONLEDGEMENTS I wish to express my gratitude to my major professor Dr. Irvin Hidders for his guidance, advice and encouragement during the course of my graduate studies and research. I also extend my appreciation to the other members of my guidance committee, Dr. Hugh Price and Dr. Darryl Harncke for their advice and constructive criticism. I gratefully acknowledge the financial support provided by Agriculture Canada during my educational leave. Finally, I wish to thank Mr. William Balkwill for his excellent technical assistance and Mrs. Natalie Abramovich for typing this thesis. TABLE OF CONTENTS PAGE LIST OF TABLES ........................... iv LIST OF FIGURES ........................... vi CHAPTER I INTRODUCTION .......................... 1 LITERATURE REVIEW ....................... 4 LITERATURE CITED ........... . ............ 15 CHAPTER II THE INFLUENCE OF N AND P NUTRITION 0N TOMATO TRANSPLANT ESTABLISHMENT Abstract ............................ 18 Introduction .......................... 19 Material and Methods ...................... 20 Results ............................ 28 Discussion ........................... 53 Literature Cited ........................ 59 CHAPTER III THE EFFECTS OF PRETRANSPLANT FERTILIZATION ON NUTRIENT STATUS OF TOMATO SEEDLINGS Abstract ............................ 61 Introduction. . . . ...... . ...... . ........ 62 Material and Methods ...................... 63 Results and Discussion ................. . . . . 65 Literature Cited ........................ 90 SUMMARY. . . . . . . . . . . ....... . . . ....... 92 APPENDICES . . . ................. . . ....... 96 iii Table 11. LIST OF TABLES Chapter II Page Composition of nutrient treatment solutions used to fertilize tomato seedlings during a 5 or 10 day pretransplant period ..................... 22 The influence of pretransplant nutrient treatments on tissue concentrations of total N and P and soluble N03 and P at transplanting (Harrow 1986) ............. 29 The influence of pretransplant treatment duration on the concentrations of total N, nitrate, total P and soluble P and dry weight of shoot tissue at planting (Harrow 1986.) ......... . .............. 32 The influence of nutrient history and pretransplant nutrient treatments on shoot tissue concentrations of total N nitrate, total P and soluble P at transplanting (East Lansing 1987) ..................... 33 The influence of nutrient history and pretransplant nutrient treatments on dry weight of tomato shoots following transplanting (Late planting, East Lansing 1987) ............................ 34 The influence of nutrient history and pretransplant nutrient treatments on dry weight of tomato shoots following transplanting (Early planting, East Lansing 1987) .................. . ......... 40 The influence of temperature on root and shoot growth of tomato seedlings at 3 and 5 days after transplanting ........................ 42 The influence of pretransplant nutrition on early shoot growth of tomato seedlings at 25°C and 14.5°C growing temperatures ......................... 43 The influence of nutrient history and pretransplant nutrient treatments on tomato root length at 3 and 5 days after transplanting (East Lansing 1987) ......... 44 The influence of pretransplant nutrition on early root growth of tomato seedlings at 25°C and 14.5“C growing temperatures. .................. . . . . . .45 The influence of pretransplant phosphorus fertilization on N and P content of tomato shoot tissue at 7, 14 and 28 days after transplanting (Harrow 1987) . ..... . . . .47 The influence of pretransplant nutrient treatments on final plant stand and fruit yield of processing tomato plug transplants (Harrow 1986) ............... .48 The influence of pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Harrow 1987) ................ 49 The influence of nutrient history and pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Early planting, East Lansing 1987) ................. 50 The influence of nutrient history and pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Late planting, East Lansing 1987) ................. 51 Chapter III The influence of fertilization during seedling culture (nutrient history) and pretransplant nutrient treatments on dry weight of tomato shoots .......... 66 The influence of fertilization during seedling culture (nutrient history) and pretransplant nutrient treatments on total N concentrations in tomato shoot tissue during a 12 day treatment period ........... 70 The influence of fertilization during seedling culture (nutrient history) and pretransplant nutrient treatments on total P concentrations in tomato shoot tissue during a 12 day treatment period ........... 71 LIST OF FIGURES Figure Chapter II Page 1. The influence of pretransplant treatment duration on shoot growth of tomato transplants up to 28 days after transplanting (Early Planting, Harrow 1986) ........... 30 The influence of nitrogen concentration in pretransplant treatment solutions on shoot growth of tomato transplants up to 28 days after transplanting (Early planting, Harrow 1986) .............................. 36 The influence of planting date and phosphorus concentration in pretransplant treatment solutions on shoot growth of tomato transplants up to 28 days after transplanting (Harrow 1987) .......................... 38 Chapter III The influence of nutrition during transplant culture on tomato shoot growth over a 12 day period, after the initiation of pretransplant nutrient treatments ........ .67 The influence of nitrogen concentration in pretransplant nutrient solutions on changes in shoot tissue total n concentration of tomato seedlings over a 12 day period ..... 72 The influence of N concentration in pretransplant nutrient solutions on total N content of tomato shoots over a 12 day treatment period . . . . . . . ................ .74 The influence of P concentration in pretransplant nutrient solutions on total P content of tomato shoots over a 12 day treatment period ................ . ....... 78 The influence of nitrogen concentration in pretransplant nutrient solutions on N uptake rate of tomato seedlings cultured at two different nutrient levels. . . . . . . . . . . .80 The influence of fertility level during transplant culture (nutrient history) on relative N uptake rate (N uptake per gram of shoot dry weight) of tomato seedlings over a 12 day period ............................. 82 The influence of phosphorus concentration in pretransplant nutrient solutions on P uptake rate of tomato seedlings cultured at two different nutrient levels ...... . ..... 84 The influence of fertility level during transplant culture on relative P uptake rate (P uptake per gram of shoot dry weight) of tomato seedlings over a 12 day period. . . . . . .87 vi INTRODUCTION One of the most important inputs in the production of many vegetable crops is the use of high quality transplants. Transplants are used to establish the majority of the processing tomato acreage in the midwestern United States and Ontario. Transplants have been preferred over direct seeding in these areas because they enable growers to achieve an earlier maturing crop and an extended harvest season, and are more reliable in terms of stand and consistent yield. Most of the processing tomato transplants are produced by specialized seedling growers on farms in southern Georgia. Over 800 million tomato transplants are produced annually by these growers (Risse et. al. 1985). This has been a profitable crop for the Georgia plant growers and has provided a source of relatively inexpensive, good quality transplants for northern tomato growers. Hhile Georgia transplants have traditionally been reliable, several problems have become more prevalent in recent years. There are often problems in scheduling of pulling and shipment of southern plants to correspond to planting schedules in the north. If weather conditions are unfavorable for transplanting, the seedlings may have to be stored. These bare root transplants have a limited storage life and are often unsuitable for planting if stored for an extended period. In recent years, disease problems have become increasingly serious in Georgia transplants. The practice of clipping the transplant beds to control growth may be partly responsible for the increased incidence of disease in southern plants. 2 These factors have prompted tomato growers to look for alternate sources of transplants. Local production of transplants would overcome the problems of scheduling delivery of southern plants, and eliminate losses due to storage of bare root plants. Growers would also have more control over seedling quality if local greenhouse grown transplants were used. Over the years, a limited number of seedlings have been produced in greenhouses using conventional ground bed methods. However, these plants have tended to be inconsistant in field performance. Economic studies have indicated that the cost of producing local ground bed plants is 10 to 30 percent higher than the cost of Georgia transplants (Fisher 1985). If local transplant growers are to be economically competitive they must be capable of producing high quality plants at a very high density in the greenhouse. A number of companies have developed systems for producing vegetable transplants in various types of seedling trays. These container systems have rapidly become the state of the art in vegetable transplant technology. Tomato transplants have been produced successfully by a limited number of growers, in small plug trays used in the bedding plant industry. An economic study conducted in Ontario (Fisher 1985), indicated that tomato transplants could be produced at a comparable cost to southern plants, using 288 cell plug trays. Therefore, the plug tray system appears to have potential as a transplant production alternative for the processing tomato industry. 3 While the use of very small container sizes makes local transplant production economically feasible, it requires excellent grower management to produce high quality seedlings. Growers must optimize their production practices in order to produce transplants that are able to withstand the stresses of adverse field conditions, to resume growth quickly and to produce a uniform, high yielding crop. Proper fertilization is an important factor in the production of many vegetable seedlings, however, its affects on the growth and development of plug tray grown tomato transplants is unknown. It was hypothesized that the management of nitrogen and phosphorus nutrition during greenhouse production of tomato transplants should influence establishment after field setting. The purpose of this study was therefore to gain a better understanding of the influence of plant nutrient status on transplant establishment, and identify nutritional factors which can be managed to produce optimum quality transplants. The approach was to determine: 1. The effects of varying rates of nitrogen and phosphorus fertilizer on nutrient uptake and seedling nutrient status at planting. 2. The influence of nutrient status on early growth, nutrient uptake, plant stand and yield. 3. The effect of various environmental conditions on early seedling growth. LITERATURE REVIEW A. Transplant Production Systems Some of the earliest and most important research on the subject of vegetable crop production has addressed the cultural requirements of transplants. The importance of using good quality transplants has been well documented in a number of vegetable crops (Loomis 1924, Romshe 1954). Romshe (1954) demonstrated the advantages of using greenhouse grown transplants in experiments conducted in Oklahoma in the early 1950's. In these studies, greenhouse grown tomato plants outyielded southern, field grown plants by almost 50 percent. Reduced plant stands due to poor survivability accounted for the lower yields with southern plants. Several researchers have studied the cultural requirements of transplant production using conventional greenhouse systems. These studies demonstrate the importance of the physiological condition of the transplant at the time of field setting. Casseres (1947) and Nicklow and Minges (1963) demonstrated that the age of the transplant affected its performance in the field. Flat grown seedlings of five to seven weeks old, produced significantly higher yields and greater fruitsize than older plants. It was also demonstrated that spacing of seedlings in the flat affected transplant performance. Casseres (1947) reported that plants grown at a wide spacing (4 inches X 4 inches) produced significantly higher early and total yields than those grown at a narrow (2 inch X 2 inch) spacing. Nicklow and Minges (1963) suggested that for high total yields, a young transplant without flower buds is desirable but if earliness is important, a larger more advanced plant is superior. In all cases the use of old, overly hardened plants should be avoided. 4 5 Another factor which has been found to influence transplant performance is the type of plant growing container used. The traditional method of tomato seedling production involved the use of ground beds or open flats. A number of researchers have demonstrated an advantage in the use of individual containers for tomato transplant production. Romshe (1954I reported that the use of 2 X 2 inch plant bands resulted in increased yields compared to plants spaced 2 X 2 inches in flats. Westover (1942) found that tomato plants grown in 3 inch pots gave increased early yields over flat grown plants. Knavel (1965) found that tomato plants grown in peat pots produced significantly higher early and total yields than flat grown plants. Larger peat pots (4 inch) produced larger transplants and higher yields than smaller pots (25 inch). The main advantage in using pots or plant bands is that root damage is minimized when the plants are set in the field (Knavel 1965). In recent years, new systems have been developed for growing transplants using various types of seedling trays. These trays are made of plastic or other synthetic materials, formed into individual containers or cells. Cell size, shape and number per tray vary depending on the intended usage of the tray. The choice of container size is an important decision for the grower because it determines the number of plants produced per unit of greenhouse space and the cost per plant. Dufault and Waters (1985) reported that with various Speedling type containers, transplant cost ranged from 1.9 cents/plant for the smallest cell size to 7.3 cents/plant for the largest size. A number of researchers have studied the effects of the various cell sizes on transplant performance. It appears that while very small cell sizes reduce seedling cost they also reduce the plant's early yield potential. However, small cells may be used if earliness is not a major 6 consideration. Dufault and Waters (1985) studies the growth of cauliflower and broccoli transplants in various sized Speedling trays. They found that with cauliflower larger cell sizes generally did not produce earlier maturity or higher yields. Broccoli plants grown in large volume containers produced higher early yields than those grown in small containers. There were no differences in total yield between the container sizes. Weston and Zandstra (1986) studied the effect of cell size on fresh market tomato production. Tomato transplants were grown in Speedling trays ranging in cell volume from 4.4 cm3 to 39.5 cm3. They found that as the cell volume increased, early fruit yield also increased. Although larger cell sizes promoted earlier production, there were not significant differences in total yield between large and small cell sizes. Kretchman and Short (1975) studied the use of Speedling type transplants for processing tomato crop establishment. There were no significant differences in crop yield between 1 inch and 2 inch Speedling cells and Georgia grown transplants. The 2 inch Speedling plants had more overmature fruit than other treatments, possibly indicating a slightly earlier maturity. A number of cultural factors contribute to the rate of establishment of vegetable transplants after field setting. One of the most important is the mineral nutrient status of the seedling. In most transplant production systems, the addition of fertilizer is necessary to produce high quality plants. Several studies have demonstrated that fertilization practices in the greenhouse can affect the early growth, stand and yield of many vegetable crops. 7 Brasher (1941) demonstrated that treatment of tomato seedlings with various nutrient solutions influenced the field performance of the plants. In this study, plants which were adequately fertilized were larger at field setting time, and were more vigorous after transplanting in the field. These plants produced significantly greater early and total yields than plants which were fertilized with low levels of nitrogen or high levels of potassium. Weston and Zandstra (1986) reported that pretransplant fertilization affected growth and yield of Speedling grown fresh market tomato plants. Transplants which were grown with low rates of fertilizer were smaller and less vigorous than adequately fertilized plants. The low fertilizer plants produced significantly lower early yields but total yields were not significantly different between the two treatments. 8. Nitrogen Nutrition Nitrogen is one of the most important plant nutrients. Nitrogen usually comprises between 1 to 5% of a plants dry weight (Tisdale et al. 1985). Nitrogen is critical to plant growth because it is a component of amino acids, proteins and nucleic acids. In plant shoot tissue, protein N accounts for about 852 of the total N, nucleic acids account for about 10% and soluble amino N, about 5% (Mengel & Kirkby 1982). Nitrogen may be absorbed by plants in the form of nitrate or ammonium ions. In most situations the N03 form is dominant (Tisdale et al. 1985). Uptake of nitrate can occur against an electrochemical gradiant, indicating that uptake is an active, metabolically controlled process (Mengel a Kirkby 1982). 8 The form of N absorbed by the plant has an important effect on plant growth. Maynard and Barker (1969) found that growth of bean, pea, corn and cucumber plants cultured in solutions with ammonium as the N source was reduced by approximately 50% compared to plants grown with nitrate as the N source. Gibson and Pill (1983) also found that ammonium nutrition reduced dry weight and growth rate of shoots, but did not affect fruit yield. A number of factors are involved in the uptake and assimilation of ammonium and nitrate by plants. Uptake of either nitrogen form is affected by the pH of the growing media. Ammonium uptake occurs best in a neutral medium while nitrate absorption occurs more rapidly at lower pH (Rao and Rains 1976). The media in which a plant is grown may also influence ammonium uptake. Tomato plants grown in peat had much less uncomplexed NH4 in shoot tissue and less foliar symptoms of ammonium toxicity than plants grown in sand or solution culture (Magalhaes and Wilcox 1984). The relative uptake of nitrate and ammonium ions is also dependent on temperature. Clarkson and Warner (1979) found that at temperatures less than 14°C the absorption of NH4 greatly exceeded that of N03 in two ryegrass species. They suggested that this may be due to physical changes in the cell membrane at lower temperatures. A similar response was seen in lettuce, in which NH4 uptake is greater than N04 uptake at temperatures less than 13°C at 18°C NH4 and N03 uptake were approximately equal and N03 uptake was greater at 23°C (Frota and Tucker 1972). Gomez-Lepe and Ulrich (1974) demonstrated that nitrogen fertilization promotes vegetative growth of the shoot. Nitrogen deficiency reduced shoot growth much more than root growth, reducing the 9 shoot to root ratio. Relatively high concentrations of N in nutrient solutions increased the shoot to root ratio. This resulted in greater succulence and an increased tendency to wilt upon exposure to low soil moisture levels. At low N levels, an increase in N supply increased growth dramatically at first and then by smaller increments with each addition. When N was in levels which were sufficient for rapid growth, additional supplies of N did not increase growth. Critical concentrations for nitrogen in plant tissue have been determined. Nitrate N, (soluble in 2% acetic acid) has been found to be a good indicator of plant nitrogen status. Lorenz and Tyler (1976) determined that NO3-N concentrations in mature leaf petiole tissue, varied depending on the stage of development of the crop. In tomato plants at the early bloom stage, 8,000 ppm N03-N is a deficient level and 12,000 ppm is a sufficient level. C. Phosphorus Nutrition Phosphorus is classed as a macronutrient and is one of the essential elements for plant growth. Phosphorus has several essential functions in plants, the most important of which is the storage and transfer of energy. Energy obtained from photosynthesis and carbohydrate metabolism is stored in phosphate containing compounds and can be used to power active processes such as ion uptake. Phosphoprus is also a constituent of nucleic acids, phospholipids (components of biological membranes) and phytin (a compound involved in seed germination) (Mengel and Kirkby 1982). Phosphorus is absorbed by plants as the H2P04 or the HP04 ion, with the H2P04 form being preferred (Munson 1978). Phosphorus uptake is an active process, probably driven by respiratory carbohydrate metabolism. The phosphorus concentration in roots ranges from 100 to 1000 times 10 higher than that of the soil solution, indicating that phosphorus uptake occurs against a steep concentration gradiant (Mengel and Kirkby 1982). A number of factors are known to affect the rate of phosphorus uptake. Root morphological features such as the number of roots and root branching affect ion uptake by determining the root surface area exposed to the soil solution (Munson 1978). Fontes and Wilcox (1984) found that an increase in root surface development resulted in an increase in P uptake. Increasing temperature increases root growth and P uptake and translocation within a plant (Munson 1978). Phosphorus status of the plant has also been demonstrated to affect P uptake. Clarkson and Scattergood (1978) found that the phosphorus uptake capacity of tomato plants was highest after phosphate supply was discontinued when the plants were beginning to show deficiency symptoms. As deficiency symptoms intensified, phosphorus uptake decreased. Fontes and Wilcox (1984) determined that tomato plants used P more efficiently (had a higher dry weight accumulation per unit of P absorbed) at low P concentration in solution that at high P concentrations. One of the most important effects of phosphorus fertilization is the improvement of early seedling growth under cold soil conditions. Wilcox (1967) found that a high P fertilizer banded below tomato seed resulted in an increased seedling growth rate from 10 to 35 days after emergence. Locascio and Warren (1959) reported that a high phosphorus starter fertilizer applied at transplanting, greatly stimulated top growth of young tomato seedlings. Phosphorus did not significantly increase the rate of root growth. Wilcox and Langston (1959) reported that direct seeded tomato seedling growth was increased by both nitrogen and phosphorus in the starter fertilizer. Transplanted tomatoes only showed a growth response 11 with the addition of N to the starter fertilizer. The difference in response between seeded and transplanted tomatoes may be because the seedling carries a nutrient reserve which may be drawn upon as the root system becomes established, while the seed must establish its root system before it can begin to take up nutrients. Therefore, a readily available source of phosphorus is more beneficial to the seeded crop. Other researchers have determined that phosphorus nutrition improves the productivity of the tomato plant beyond a stimulation of early growth. Gibson and Pill (1983) found than increasing concentrations of P in growing media decreased shoot and root growth but increased fruit yield in greenhouse tomatoes. Besford (1979) reported that inadequate levels of P nutrition reduced fruitset and yield of tomato plants. Plant tissue analysis has been used as an aid in determining the phosphorus fertility requirements of a crop. Most researchers have found that soluble P (PO4-P soluble in 2% acetic acid) provides a better measure of the plants P status than total P (Lorenz and Vittum 1980). The critical level of soluble P04-P for tomatoes at most growth stages is 2000 ppm in mature leaf petiole tissue (Lorenz and Vittum 1980). 0. Nutrition and Transplant Establishment Nitrogen and phosphorus nutrition of transplants has been studied on several different vegetable crops. It appears that the nutritional requirements of transplants vary depending on the crop and the plant production system used. In a study on asparagus transplant quality, Adler et al. (1984) found that mineral nutrition affected the partitioning of dry weight between roots, crowns and shoots. Increasing rates of N favored the 12 partitioning of dry weight into the shoots. Increasing rates of potassium decreased the production of fleshy roots. Increasing rates of phosphorus favored partitioning of dry weight into crowns, thereby increasing the crown to shoot ratio. This is desirable because the conservation of carbohydrates in the crown may encourage rapid growth after transplanting. They recommended a fertility regime of 100 ppm N and K and 20 ppm P for optimum transplant quality. A similar study on celery transplants (Dufault 1985) indicated a different nutritional requirement. As nitrogen rate increased, root and shoot dry weight increased and foliage color was improved. Increasing rates of phosphorus increased seedling diameter, height and root and shoot dry weight. Increasing potassium rates had no effect on seedling size dry weight or quality. Celery seedlings grown at low N and P rates were stunted, spindly and unacceptable for commercial planting. A feeding program consisting of 250 ppm N, 125 ppm P and 10 ppm K, applied weekly was identified as being acceptable for celery transplant production. Dufault (1986) evaluated the affects of fertilization on container grown muskmelon transplants. High levels of nitrogen (250 ppm applied twice weekly) increased seedling height, dry weight, and shoot to root ratio. Nitrogen at 250 ppm combined with phosphorus at 5 ppm resulted in an increased incidence of transplant shock (leaf necrosis). The addition of P at 125 ppm reduced the incidence of transplant shock and improved early growth. High phosphorus concentrations enchanced root growth while high potassium concentrations increased seedling height leaf area and stem diameter. A nutrient regime consisting of 250 ppm N, 13 125 ppm P and 250 ppm K applied twice weekly was suggested as the optimum program for production of high quality, vigorous muskmelon transplants. Knavel (1977) studied the influence of nitrogen fertilizer on growth and yield of pepper transplants. Seedlings which were grown with the highest levels of N (360 grams of N per cubic metre of growing media) had larger leaves, darker color and higher fresh weight than any other treatment. These plants also had the highest total N and total P concentration in the tissue. The plants which were grown with low N levels (180 gm/m3) were light green and exhibited nitrogen deficiency symptoms at transplanting time. The plants grown with the 300 g/m3 nitrogen treatment were higher yielding than plants grown with lower or higher levels. A nitrogen concentration of 3.72 in leaf tissue at planting was determined to be the optimum level for transplant performance. A number of studies have been conducted on the fertility requirements of southern, field-grown processing tomato transplants. Murphy (1964) studied the affects of phosphorus and potassium fertilizers applied to the plant beds before seeding the tomato crop. He found that a 100 lb/acre rate of K tended to produce smaller plants and lower yields of marketable plants than the 50 lb/acre rate. Increasing P rates from 10 to 70 pounds per acre resulted in increased plant height and dry weight. In treatments where P was not applied, the plants showed typical phosphorus deficiency symptoms. The highest rate of P produced greater yields of marketable plants and reduced plant growing time in early seeded crops. 14 Jaworski (1966) found that yields of marketable transplants were improved by high N and high P rates. A nitrogen rate of 40 to 60 lbs/acre was the optimum rate for transplant quality and seedling yield. He stated that phosphorus is the most important element limiting high plant yields. Fertilization with P at 60 pounds per acre resulted in greater transplant uniformity and higher yields of marketable seedlings per acre, compared to a 10 pound per acre application. Jaworski and Webb (1966) found that N and P nutrition affected transplant performance after transplanting in Ohio. Transplants which were grown with either high NP levels (60 lb/acre N and 90 lb/acre P) or low NP levels (20 lb/acre N and 10 lb/acre P) produced high fruit yields. Transplants grown with high N and low P levels (60 lb/acre N and 10 lb/acre P) produced significantly lower fruit yields. Jaworski Webb and Morton (1967) found that fertilization with high nitrogen and low phosphorus levels tended to reduce plant survival after extended periods of storage. In general plant storage life was improved by high N and high P levels of field fertilization. 10. 11. 12. 13. LITERATURE CITED Adler, P. R., R. J. Dufault and L. Waters Jr. 1984. Influence of nitrogen, phosphorus, and potassium on asparagus transplant quality. Hort. Science 19(4): 565-566. Besford, R. T. 1979. Effect of phosphorus nutrition in peat on tomato plant growth and fruit development. Plant & Soil 51:341-353. Brasher, E. P. 1941. Growth and yield of the tomato plant when hardened with certain nutrient solutions. Proc. Amer. Soc. Hort. Sci. 38:629-632. Casseres, E. H. 1947. Effect of date of sowing, spacing and foliage trimming of plants in flats on yield of tomatoes. Proc. Amer. Soc. Hort. Sci. 50:285-289. Clarkson, 0. T. and C. B. Scattergood. 1982. Growth and phosphate transport in barley and tomato plants during the development of and recovery from phosphate stress. J. Exp. Bot. 33:865-875. Clarkson, D. T. and Warner, A. J. 1979. Relationship between root temperature and the transport of ammonium and nitrate ions by Italian and perennial ryegrass. Plant Physiol. 64:557-561. Dufault, R. J. 1985. Relationships among nitrogen, phosphorus and potassium fertility regimes on celery transplant growth. Hort. Science 20(6):1104-1106. Dufault, R. J. 1986. Influence of nutritional conditioning on muskmelon transplant quality and early yield. J. Amer. Soc. Hort. Sci. 111(5):698-703. Dufault, R. J. and L. Waters Jr. 1985. Container size influences broccoli and cauliflower transplant growth but not yield. Hort. Science 20(4):682-684. Fisher, G. A. 1985. Preliminary report on processing tomato transplant production 1985. Ontario Ministry of Agriculture and Food. Chatham, Ontario. Fontes, P. C. R. and G. E. Wilcox 1984. Growth and phosphorus concentrations in soil and nutrient solutions. J. Amer. Soc. Hort. Sci. 109(5):633-636. Frota, J. N. E. and T. C. Tucker 1972. Temperature influence on ammonium and nitrate absorption by lettuce. Soil Sci. Soc. Am. Proc. 36:97-100. Gibson, C. J. and W. G. Pill 1983. Effects of preplant phosphorus fertilization rate and of nitrate and ammonium liquid feeds on tomato growth in peat-vermiculite. J. Amer. Soc. Hort. Sci. 108(6):1007-1011. 15 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 16 Gomez—Lepe, B. E. and Ulrich, A. 1974. Influence of nitrate on tomato growth. J. Amer. Soc. Hort. Sci. 99(1):45—49. Jaworski, C. A. 1966. Yield and growth uniformity of tomato transplants in relation to nutrition levels. Proc. Amer. Soc. Hort. Sci. 89:577-583. Jaworski, C. A. and R. E. Webb 1966. Influence of nutrition, clipping and storage of tomato transplants on survival and yield. Proc. Fla. State Hort. Soc. 79:216-221. Jaworski, C. A., R. E. Webb and D. J. Morton 1967. Effects of storage and nutrition on tomato transplant quality, survival and fruit yield. Hort. Res. Vol 7:90-96. Knavel, D. E. 1965. Influence of container, container size, and spacing on growth of transplants and yields in tomato. Proc. Amer. Soc. Hort. Sci. 86:582-586. Knavel, D. E. 1977. The influence of nitrogen on pepper transplant growth and yielding potential of plants grown with different levels of soil nitrogen. J. Amer. Soc. Hort. Sci. 102(5):533-535. Kretchman, D. W. and T. H. Short. 1975. An initial evaluation of "Speedling“ transplants for processing tomatoes. Ohio Agr. Res. and Dev. Center. Wooster. Res. Summary 81. Locascio, S. J. and G. F. Warren 1959. Growth pattern of the roots of tomato seedlings. Proc. Amer. Soc. Hort. Sci. 74:494-499. Loomis, W. E. 1924. Studies in the transplanting of vegetable plants. N.Y. (Cornell) Agr. Exp. Sta. Memoir 87. Magalhaes, J. R. and G. E. Wilcox. 1984. Growth, free amino acids and mineral composition of tomato plants in relation to nitrogen form and growing media. J. Amer. Soc. Hort. Sci. 109(3):406-411. Maynard, D. N. and Barker, A. V. 1969. Studies in the tolerance of plants to ammonium nutrition. J. Amer. Soc. Hort. Sci. 94:235-239. Mengel, K. and E. A. Kirkby. 1982. Principles of plant nutrition. 3rd edition. (Berne, Switzerland:International Potash Institute). Murphy, W. S. 1964. Phosphorus and potassium nutrition of southern tomato transplants. Proc. Amer. Soc. Hort. Sci. 85:478-483. Nicklow, C. W. and P. A. Minges 1963. Plant growing factors influencing the field performance of the Fireball tomato variety. Proc. Amer. Soc. Hort. Sci. 81:443-450. Rao, K. P. and Rains, D. W. 1976. Nitrate absorption by barley. Plant Physiol. 57:55-58. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 17 Risse, L. A., D. W. Kretchman and C. A. Jaworski 1985. Quality and field performance of densely packed tomato transplants during shipment and storage. Hort. Science 20(3):438-439. Romshe, G. A. 1954. Studies of plant production methods for vegetable crops: cabbage-tomato-onions-melons and cucumbers. Okla. Bull. B-421:5-15. Tiessen, H. and Carolus. 1963. Effects of soluble starter fertilizer and air and soil temperatures on growtrh and petiole composition of tomato plants. Proc. Amer. Soc. Hort. Sci. 82:403-413. 1963. Tiessen, H. and R. L. Carolus 1963. Effect of different analyses and concentrations of fertilizer solutions on initial root growth of tomato and tobacco plants. Proc. Amer. Soc. Hort. Sci. 83:680-681. Tisdale, S. L., W. L. Nelson and J. D. Beaton. 1985. Soil Fertility and Fertilizers Fourth Edition, (New YorkzMacmillan Publishing Company). Ware, G. W. and J. P. McCollum 1980. Producing Vegetable Crops, 3rd edition, (Danville Illinois: The Interstate Printers and Publishers Inc.). Weston, L. A. and B. H. Zandstra 1986. Effect of root container size and location of production on growth and yield of tomato transplants. J. Amer. Soc. Hort. Sci. 111(4):498-501. Westover, K. C. 1942. Further studies on the effect of topping young tomato plants on fruit set and yield. Proc. Amer. Soc. Hort. Sci. 41:285-289. Wilcox, G. E. 1967. Effect of phosphorus fertilization on tomato seedling growth rate. Proc. Amer. Soc. Hort. Sci. 90:330-334. Wilcox, G. E. and R. Langston 1959. Effect of starter fertilization on early growth and nutrition of direct seeded and transplanted tomatoes. Proc. Amer. Soc. Hort. Sci. 75:584-594. THE INFLUENCE OF N AND P NUTRITION ON TOMATO TRANSPLANT ESTABLISHMENT ABSTRACT Studies were conducted to evaluate the importance of nitrogen (N) and phosphorus (P) nutrition during transplant production, on establishment and yield of processing tomatoes. Tomato (Lycopersicon esculentgp Mill.) seedlings were grown in 288 cell plug trays in soilless growing media. The nutrient status of the plants was altered by the utilization of nutrient solutions containing N in concentrations ranging from 140 to 280 ppm and P in concentrations ranging from 62 to 155 ppm. Treatment with the nutrient solutions for 10 days before transplanting enhanced total N and P, nitrate and soluble P concentrations and contents in the plant. Following transplanting, both shoot and root growth were stimulated by increases in temperature and high N treatments. High N pretransplant treatments resulted in reduced plant stands in early season plantings. High P treatment concentrations improved plant surviveability following transplanting and resulted in higher marketable yields for the early planting date. Transplants which were treated with a relatively high fertility regime (150 ppm N, 64 ppm P and 125 ppm K) during greenhouse culture, produced lower fruit yields than plants grown with a 75 N, 32 P and 62 K treatment. Withholding fertilizer prior to transplanting reduced tissue nutrient concentration, and plant growth after field setting and resulted in lower fruit yields. Nutrition treatments did not affect growth, stand or yield in a late-season planting. 18 INTRODUCTION In recent years, processing tomato growers in the midwestern United States have sought to develop systems for producing transplants in greenhouses. A number of growers have started commercial production of tomato transplants in 288 cell plug type trays. The use of these small cells allow for the production of transplants at high densities in the greenhouse, thus making it cost competitive with other transplant sources. However, relatively little is known about the exact cultural inputs needed to produce high quality transplants using plug systems. The use of small volume plugs to produce transplants may create a number of unique problems. Root and shoot development of the seedling is limited by the small plug. Thus, immediately after field setting, the seedling has a limited root system for water uptake, and a relatively small reserve of nutrients which may be used to initiate growth. The small plug size may create more problems of root binding if the seedling is not transplanted at a young stage of development. Successful production of plug transplants will require a thorough understanding of the effects of cultural practices on transplant establishment. Cultural practices used in producing transplants are known to affect plant establishment and crop yield (14). Brasher (3) reported that fertilization practices during transplant production affected field performance. Excessive rates of potassium or insufficient rates of nitrogen fertilizer resulted in stunted plants and reduced early yields. Weston and Zandstra (18) reported that fresh market tomato plants grown in small volume Speedling cells had lower early yields than 19 20 . larger cells, but generally did not have lower total yields. Improper nutrition of Speedling grown plants prior to field setting, delayed plant establishment and lowered early yields. Jaworski and Webb (8) found that ground bed grown plants which were fertilized with high nitrogen and low phosphorus rates were lower yielding than plants fertilized with either high or low rates of both. The objective of these studies was to determine the influence of nitrogen and phosphorus fertilization practices during greenhouse production on field performance of plug tray grown, processing tomato transplants. Nitrogen and phosphorus status of transplants was altered using various fertilizer treatments. The influence of plant nutrient status on seedling growth, nutrient uptake, plant survival and fruit yield was evaluated. MATERIALS AND METHODS EXPERIMENT # 1 AND 2 (Harrow 1986 ppd 1987) Field experiments were conducted at the Agriculture Canada Research Station at Harrow, Ontario in 1986 and 87. The soil type for both experiments was a Fox sandy loam (Brunisolic Gray Brown Luvisol, Typic Hapludalf) with a pH of 6.4. Soil tests indicated fertility levels of 80 ppm available P and 240 ppm available K. No additional P or K fertilizer was applied. Prior to transplanting, the soil was fertilized with 80 Kg/ha of nitrogen. Seeds of processing tomato (Lycopersicon esculentum cv. H2653, H.J. Heinz Co.) were sown in 288 cell plug trays (TLC Polyform, Plymouth, Minnesota), containing ASB growing media (ASB Greenworld Ltd, Waterloo, Ontario). Seeding was done of April 1, 1986 and March 24, 21 1987 to produce transplants for an early May planting date. Plants for a late May planting were seeded on April 18, 1986 and April 16, 1987. The trays were placed in a chamber at a temperature of 23°C for four days until seedling emergence. The trays were moved into a glass greenhouse. Minimum growing temperature was 13°C while maximum temperature varied with ambient conditions up to 35°C. The seedlings were fertilized three times weekly with Peter's 20-20-20 soluble fertilizer (20N - 8.6P - 16.6K) applied in water. A fertilizer concentration of 60 ppm N, 26 ppm P and 50 ppm K was used in order to produce plants with a relatively low nutrient status and to avoid excessively rapid growth. Starting at 10 days or 5 days before the scheduled transplanting dates the seedlings were subjected to four different pretransplant nutrient treatments. The treatments were factorial combinations of nitrogen (N) and phosphorus (P) in four nutrient solutions (Table 1). The solutions were applied twice daily for 10 or 5 days before transplanting. The experimental design was a 2 x 2 x 2 factorial in a randomized complete block with 4 replications. The factors were pretransplant treatment duration (10 or 5 days), nitrogen concentration (280 or 140 ppm) and phosphorus concentration (155 or 62 ppm). In 1987, treatment duration was not included as a factor, and all nutrient treatments were applied for 10 days prior to transplanting. In the 1986 trial, the early planting was transplanted into the field on May 12 and the late planting on May 28. The seedlings were transplanted using a Mechanical transplanter at a spacing of 1.5 m between rows and 30 cm between plants. The experimental units consisted 22 Table 1. Composition of nutrient treatment solutions used to fertilize tomato seedlings during a 5 or 10 day pretransplant period. Salt concentration in solution (mM) Nutrient Treatment Solution* NaH2P04.H20 NH4H2P04 KNO3 Ca(N03)2 MgSO4.7H20 NH4NO3 1. High N High P (280 ppm N 155 ppm P) 3 2 4 2 1 5 2. High N Low P (280 ppm N 62 ppm P) 2 - 4 2 1 6 3. Low N High P (140 ppm N 155 ppm P) 3 2 4 2 1 - 4. Low N Low P (140 ppm N 62 ppm P) 2 - 4 2 1 1 * Each solution contained the following additional nutrients: (156 ppm) Ca (160 ppm) Mg ( 24 ppm) S ( 32 ppm) Micronutrients were supplied using Peters Soluble Trace Element Mix and Iron chelate (EDTA) added according to recommended rates. Nutrient solutions were acidified to a final pH of 6.0 using 1.0 N H2804. 23 of single rows 20 m long. No starter fertilizer was used in the transplant water and no irrigation was provided following transplanting. All cultural practices, including herbicide and pesticide applications were according to standard commercial practices used in the area. Plant shoot samples (10 plants/sample) were collected before transplanting and at 7, 14 and 28 days after transplanting. The tissue was washed in deionized water and dried at 60°C in a forced air oven for four days. Individual plant dry weights were determined and the samples were stored for use in mineral nutrient analysis. In 1986, harvesting of fruit was done on August 15 and August 28 for the early and late plantings, respectively. Harvest dates in 1987 were August 13 and August 24. Harvesting was done when approximately 80% of the fruit on the plants were in the red ripe stage. Final plant stands were determined prior to harvest in order to evaluate plant survival. The harvested plots were 10 m long. Plots were harvested in a once over mechanical harvest, and yields of marketable fruit, green fruit and culls were recorded. EXPERIMENT # 3 (East Lansing 1987) An additional field experiment was conducted at the Michigan State University, Horticulture Research Farm, East Lansing, Michigan in 1987. The soil type was a Spinks sandy loam with a pH of 6.3 and a cation exchange capacity of 4. A soil test indicated fertility levels of 35 ppnl of available P/acre and 75 ppm available K/acre. The soil was fertilized with 80 Kg/ha N, 160 Kg/ha P and 160 Kg/ha K. 24 Processing tomatoes were seeded in 288 cell plug trays as described in Experiment # 1 and 2. Plantings were scheduled for early and late May transplanting dates. The nutritional factors studied in this experiment were: (1) Nutrient history (fertilization regime from seedling emergence to 10 days before transplanting) and (2) Pretransplant nutrient treatment (fertilization regime for 10 days before transplanting). The nutrient history treatments consisted of daily applications of Peter's 20-20-20 soluble fertilizer at regular watering times, at concentrations of 75 ppm N, 32 ppm P, 62 ppm K (low nutrient history) or 150 ppm N, 64 ppm P, 124 ppm K (high nutrient history). The early planting, low nutrient history was seeded on March 28 and the high nutrient history on April 4. The late planting low and high nutrient history treatments were seeded on April 16 and April 21 respectively. The seedings were staggered over time in order to produce seedlings of a similar developmental stage but varying nutrient status. This schedule was also intended to simulate different production schedules which growers could use to produce plants of a desirable size. The transplants were grown in a glass greenhouse where growing temperatures were maintained at a minimum night temperature of 20°C. Day temperature varied with ambient conditions up to 35°C. No supplemental lighting was provided. Ten days before the anticipated transplanting dates, the seedlings were subjected to the pretransplant nutrient treatments. Nutrient solutions varying in N and P concentration (Table 1) were applied twice daily at regular watering times. A fifth treatment was added to this experiment to evaluate the effects of withholding nutrients on 25 transplant establishment. This treatment received water with no nutrients added during the 10 day pretransplant period. The experimental design was a 2 x 5 factorial in a randomized complete block with 3 replications, with the factors being nutrient history and pretransplant nutrient treatment. The experimental units were single rows, 22 m in length, with a 17 m section for plant sampling and a 5 m section for fruit yield determination. The early planting was transplanted on May 12 and the late planting on May 28. All transplanting practices and other crop management practices were as described in experiment I and 2. Plant shoot samples (10 plants) for dry weight and nutrient determinations were collected as described in experiment # 1. and 2. Samples were taken at 3, 5, 7, 14 and 28 days after transplanting. Plant root samples were excavated at 3 and 5 days after transplanting to determine treatment effects on root growth. Roots were washed to separate soil, and the new roots which had grown from the plug and stem were excised. Root length was determined by the root intersection method described by Newman (13). Harvesting of fruit was done on August 17 and August 31 for early and late plantings, respectively, using a once over hand harvest. Final plant stand and yields of marketable, green and cull fruits were recorded. EXPERIMENT # 4 This experiment was conducted in controlled environment chambers in order to evaluate the influence of temperature on tomato transplant establishment. Tomatoes (cv. H2653, H. J. Heinz Co.) were seeded in 288 26 cell plug trays containing ASB growing mix. The seedlings were grown in a glass greenhouse with a minimum night temperature of 20°C and a maximum day temperature of 28°C. The plants were fertilized three times weekly with Peter's 20-20-20 fertilizer at 60 ppm N, 26 pp"! P and 50 ppm K. When the plants were 25 days old and in the 5 true leaf stage, they were subjected to the pretransplant nutrient solutions described in Table 1. These treatments were applied twice daily for 10 days. Seedlings of each of the four nutrient treatments were transplanted into a sterilized sandy loam soil in 15 cm clay pots. The filled pots were placed in the growth chambers for 24 hours prior to transplanting to allow the soil temperatures to equilibrate. After transplanting, half the seedlings of each nutrient treatment were moved to two constant temperature chambers. The high temperature chamber was maintained at 25°C and the low temperature chamber at 14.5°C. Daylength in both chambers was 16 hours and light intensity was approximately 450 E/mZ/S. The pots were watered lightly, three times daily to ensure that water stress did not affect root growth. The experimental design was a split plot, with temperature as the main plot and nutrient treatments as sub plots. The sub plots were arranged as a 2 x 2 factorial with N and P level as the factors. The experiment was replicated three times over time. ’Plant shoots were destructively harvested at planting and at 3 and 5 days after transplanting to evaluate growth and nutrient concentration in the tissue. Root length determinations were made for plants at 3 and 5 days after transplanting using Newmans line intercept method (13). 27 NUTRIENT ANALYSIS The dried plant tissue samples were ground to pass a 20 mesh screen in a Wiley mill. Ground tissue samples were digested using concentrated H2504. Total nitrogen was determined by a Kjeldahl procedure (2) using a Lachat ion analyser (9). For total P analysis, tissue samples were wet-ashed using perchloric acid and hydrogen peroxide as described by Adler and Wilcox (1). Total phosphorus was determined colorimetrically using the Fiske-Subarrow method (4). Samples for nitrate and soluble PO4-P analysis were extracted in a 3% acetic acid solution (4). Nitrate in solution was analysed following reduction to nitrite using a copperized cadmium column. Nitrite was determined colorimetrically using a Lachat ion analyser (9). Soluble PO4-P was determined colorimetrically using the Fiske-Subarrow method (4). STATISTICAL ANALYSIS Results of all experiments were analysed by a factorial analysis of variance. Means were separated by least significant difference at the 5% or 1% level. RESULTS Pretransplant nutrient treatments containing N at 280 ppm, increased shoot tissue concentration of total N from 3.19% to 3.86% and nitrate from .593 to 1.12% at planting, compared to 140 ppm N treatments (Table 2). Seedlings which were treated with nutrient solutions containing 155 ppm P had at pJanting tissue concentrations of total P and soluble PO4-P of .952 and .533 respectively compared to .682 and .402 for those treated with 61 ppm P (Table 2). The concentrations of N and P in nutrient solutions applied prior to transplanting did not affect shoot dry weight at transplanting. The duration of application of pretransplant nutrient treatments also affected shoot tissue nutrient concentrations at planting. The 10 day treatment duration enhanced both nitrate and PO4-P concentrations in both early and late plantings as compared to the 5 day duration (Table 3). The 10 day treatment duration increased total N in the early planting only. Treatment duration did not affect total P concentration in either planting. The 10 day treatment duration increased shoot dry weight at planting, compared to the 5 day duration (Table 3)(Figure 1). The nutrient history regime of 150 ppm N, 65 ppm P and 125 ppm K increased shoot tissue concentrations of total N and P, PO4-P and NO3-N by' 10 ‘to 152 as compared to 'the '75N, 32P, 63K regime (Table .4). Nutrient history did not affect shoot dry weight at planting in the early planting. In the late planting, the 75 ppm N, 32 ppm P and 63 ppm K treatment had a 30% greater shoot dry weight at planting (Table 5). Withholding nutrients for 10 days prior to transplanting resulted in lower shoot tissue concentrations of total N and P, NO3-N and PO4-P at planting time compared to adequately fertilized treatments (Table 4). 28 29 Table 2. The influence of pretransplant nutrient treatments on shoot tissue concentration of total N and P, and soluble N03 and P at transplanting (Harrow 1986). Tissue concentration (z dry wt.) Treatment (ppm) Total N N03-N Total P Soluble P04-P 280 N 155 P 3.922 1.11 0.90 .53 280 N 62 P 3.80 1.14 0.67 .41 140 N 155 P 3.23 .61 1.00 .53 140 N 62 P 3.15 .58 0.71 .39 F test: N ** ** ns ns P ns ns ** ** N x P ns ns ns ns 2 Each figure is the mean of 2 nutrient treatment durations X 3 replications X 2 planting dates. NS, ** nonsignificant or significant at the 1% level. 30 Figure 1. The influence of pretransplant treatment duration on shoot growth of tomato transplants up to 28 days after transplanting (Early Planting, Harrow 1986). om. 0N 02_._.Z<.._sz05 n. Eaa No I . 8m .63 a can on. mum [on 8N >36 n. Eng «0 Ole . (SiNV'ld OL/o) ELM xao .LOOHS 40 Table 6. The influence of nutrient history and pretransplant nutrient treatments on dry weight of tomato shoots following transplanting (Early planting, East Lansing 1987). Shoot dry weight (9/10 plants Days after transplanting Treatment 0 3 5 7 14 28 Nutrient History (ppm) 1.062 1.00 1.28 1.28 4.17 79.59 150 N 64 P 124 K 1.09 1.00 1.30 1.35 4.54 101.21 75 N 32 P 62 K ns ns ns ns ns * F test Pretransplant Treatment (ppm) 280 N 155 P 1.15 1.17 1.63 1.56 4.82 107.89 280 N 62 P 1.12 1.20 1.53 1.59 5.14 96.54 140 N 155 P 1.14 .95 1.24 1.25 4.61 96.01 140 N 62 P 1.13 1.05 1.33 1.46 4.49 103.58 0 N, 0 P .85 .63 .72 .73 2.70 47.98 F ta 5 t ** ** ** *‘k ** ** LSD (.01) .15 .20 .23 .37 1.43 43.06 2 Each figure is the mean of 5 final nutrient treatments x 3 replications. Y Each figure is the mean of 2 nutrient histories x 3 replications. ns, *, **, Not significant and significant and the 5 and 1% levels respectively. 41 early May planting had higher shoot dry weight at 28 days after tranSplanting due to more favorable environmental conditions (Tables 5 and 6). Under controlled temperature conditions (Experiment 4), both temperature and pretransplant nutrition affected seedling growth. The 25°C temperature treatment had higher shoot dry weights at 3 and 5 days after transplanting as compared to the 14.5°C temperature (Table 7). Under the 14.5°C regime, the 155 ppm P treatment resulted in a reduction in shoot growth at 5 days, at high N concentrations. When low N concentrations were used, P did not affect shoot growth (Table 8). Pretransplant fertilization of seedlings also affected root growth following transplanting. In the early planting of experiment 3, treatments in which nutrients were withheld, had significantly shorter root lengths at 3 and 5 days as compared to treatments which were adequately fertilized (Table 9). Treatments fertilized with 280 ppm N tended to have greater root lengths than 140 ppm N treatments in the early May planting. Nutrition treatment did not affect root length in the late May planting. Root lengths were significantly greater in the late planting (Table 9). In experiment 4, under controlled temperature conditions, pretransplant nutrition did not have a consistant effect on root length (Table 10). Higher temperatures (25°C) promoted root growth at 3 and 5 days after transplanting (Table 7). In the early planting of experiment 1, treatment with 155 ppm P increased the phosphorus content of plant shoots at 1 and 2 weeks after transplanting (data not presented). In experiment 2, pretransplant treatment with 155 ppm P increased P content at 7 and 14 days and N 42 Table 7 The influence of temperature on root and shoot growth of tomato seedlings at 3 and 5 days after transplanting. a y j Shoot dry weight (g/S plants) Root length (cm/plant) Treatment Days after transplanting Days after transplanting (temperature) 3 5 3 5 25° C .1422 .201 25.27 64.91 14.5° C .112 .130 5.19 17.13 F test ** ** ** ** 2 Each figure is the mean of 2 samples X 5 plants X 3 replications X 4 nutrient treatments. ** Significant at the 1% level. 43 Table 8. The influence of pretransplant nutrition on early shoot growth of tomato seedlings at 25°C and 14.5°C growing temperatures. Shoot Dry Weight (g) Pretransplant Days After Transplanting treatment (ppm) 0 3 High temperature (25°C) 280 N 155 P .062 .132 .187 280 N 62 P .059 .177 .246 140 N 155 P .058 .131 .184 140 N 62 P .052 .126 .188 F test: N ns ns ns P ns ns ns N x P ns ns ns Low temperature (14.5°C) 280 N 155 P .062 .106 .135 280 N 62 P .059 .119 .160 140 N 155 P .058 .111 .114 140 N 62 P .052 .112 .110 F test: N ns ns ** P ns ns ns N x P ns ns * Figures are the means of 2 samples of 5 plants x 3 replications. ns, *, ** Not significant and significant at the 5 and 1% levels respectively. 44 Table 9. The influence of nutrient history and pretransplant nutrient treatments on tomato root length at 3 and 5 days after transplanting (East Lansing, 1987). Root lengths (cm/plant) Early Late Days After Transplanting Treatment 3 5 3 5 Nutrient History (ppm) 150 N 64 P 124 K 5.72 25.7 24.1 44.0 9 75 N 32 P 62 K 6.0 26.5 26.6 57.4 *‘ F test ns ns ns ns Pretransplant Treatment (ppm) 280 N 155 P 8 7 38.5 26.1 57.3 280 N 62 P 7.3 33.3 25.2 59.0 140 N 155 P 5.6 20.8 19.7 50.8 140 N 62 P 5 O 31.6 32.4 47.1 0 N, 0 P 2.7 6.4 23.7 39.4 F test * * ns ns LSD (.05) 1.4 21.3 -- -- 2 Each figure is the mean of 5 final nutrient treatments x 3 replications. 7 Each figure is the mean of 2 nutrient histories x 3 replications. ns, * Not significant and significant at the 5 % level. 45 Table 10. The influence of pretransplant nutrition on early root growth of tomato seedlings at 25°C and 14.5°C growing temperatures. Root length (cm/plant) Days After Transplanting Treatment 3 5 High temperature (25°C) 280 N 155 P 25.93 85.22 280 N 62 P 24.16 58.83 140 N 155 P 29.79 52.60 140 N 62 P 21.21 62.99 F test: N ns ns P ns ns N x P ns ns Low temperature (14.5°C) 280 N 155 P 3.71 14.99 280 N 62 P 3.71 21.49 140 N 155 P 7.26 13.79 140 N 62 P 6.08 18.24 F test: N ns ns P ns ns N x P ns ns Figures are the means of 2 samples of 5 plants x 3 replications. ns, ** Not significant and significant at the 12 level. mm 46 content at 14 days in the early planting (Table 11). In experiment 3, plant nutrient contents after transplanting did not indicate any consistent influence of fertilizer treatment on nutrient uptake. Plant survival after transplanting and thus, final plant stand was affected by pretransplant nutrient treatments. Treatment with 280 ppm N solutions prior to transplanting resulted in reduced plant stands in the early planting of experiment 1 (significant at the 10% level). Stands were also reduced in the late plantings of experiment 1 and 2 although these were not statistically significant (Tables 12 and 13). Phosphorus treatment did not affect stand in experiment 1 (Table 12). In experiment 2, pretransplant treatment with 155 ppm P improved plant survival in both early and late plantings (Table 13). The duration of nutrient treatment did not affect plant survival. In experiment 3, nutrient history and pretransplant nutrient treatment did not affect plant stand (Tables 14 and 15). In this experiment, the late May planting had significantly better plant survival than the early planting due to more favorable temperature and moisture in late May (Tables 14 and 15). Pretransplant nutrition affected fruit yield of plug tray grown tomato transplants. In experiment 1 and 2, treatment with 155 ppm P significantly improved marketable fruit yield in the early May planting. Phosphorus treatment did not affect late planting yields. Nitrogen treatment did not affect yields in early or late plantings (Tables 14 and 15). 47 Table 11. The influence of pretransplant phosphorus fertilization on N and P content of tomato shoot tissue at 7, 14 and 28 days after transplanting (Harrow 1987). N content (g/IO plants) P content (g/IO plants) Treatment Days after transplanting Days after transplanting (ppm) 7 14 28 7 14 28 Early Planting 155 P .0562 .103 .84 .021 .029 .094 62 P .048 .074 1.01 .013 .019 .107 F test ns * ns ** ** ns Late Planting 155 P .092 .200 3.12 .028 .036 .37 62 P .109 .247 3.84 .028 .038 .48 F test * ns ns ns ns ns 2 Each figure is the mean of 2 nitrogen treatments X 4 replications. ns, *, ** not significant and significant at the 5% level or 1% level. —w 48 Table 12. The influence of pretransplant nutrient treatments on final plant stand and fruit yield of processing tomato plug transplants (Harrow 1986). Plant stand (%) Marketable yield (t/ha) Planting date Planting date Treatment (ppm) May 12 May 28 May 12 May 28 280 N 155 P 92.42 91.7 43.64 43.42 280 N 62 P 93.9 90.1 41.08 42.38 140 N 155 P 98.1 92.8 45.16 44.40 140 N 62 P 95.1 93.9 40.98 45.02 F test: N * ns ns ns P ns ns ** ns N x P ns ns ns ns 2 Each figure is the mean of 2 nutrient treatment durations X 4 replications ns, *,** nonsignificant or significant at the 102 or 5% level. '1 49 Table 13. The influence of pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Harrow 1987). Plant stand (%) Marketable yield (t/ha) Planting date Planting date Treatment (ppm) May 13 May 28 May 13 May 28 280 N 155 P 98.02 94.0 44.09 36.59 280 N 62 P 85.7 87.5 33.80 35.50 140 N 155 P 91.0 93.5 39.39 36.68 140 N 62 P 93.3 93.3 36.70 37.68 F test: N ns ns ns ns P ** 'A’ * "S N x P ** ns ns ns LSD .05 7.4 -- -- -- 2 Each figure is the mean of 4 replications ns, *, ** nonsignificant and significant at the 10% level or 5% level. 5. 50 Table 14. The influence of nutrient history and pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Early Planting, East Lansing 1987). ‘5Yield (t/ha) -__--__ Plant Marketable Treatment stand (%) fruit Greens Culls Nutrient History (ppm) 150 N 64 P 124 K 87.42 59.35 11.73 1.5 75 N 32 P 62 K 85.1 66.94 12.35 1.8 F test ns * ns ns Pretransplant Treatment (ppm) 280 N 155 P 85.7 66.49 12.33 1.17 280 N 62 P 89.7 66.16 11.03 1.88 140 N 155 P 89.7 65.19 15.22 1.73 140 N 62 P 82.8 64.50 11.93 2.44 0 N, O P 85.5 53.40 9.70 0.88 F test ns *X ns ns x Single degree of freedom orthogonal comparison between the O N, 0 P treatment and other treatments was significant at the 5% level. 2 Each figure is the mean of 5 final nutrient treatments x 3 replications. Y Each figure is the mean of 2 nutrient histories x 3 replications. 51 Table 15. The influence of nutrient history and pretransplant nutrient treatments on final plant stand and fruit yields of processing tomato plug transplants (Late planting, East Lansing, 1987). Yield (t/ha) Plant Marketable Treatment stand (%) fruit Greens Culls Nutrient History (ppm) 150 N 64 P 124 K 96.82 39.79 20.13 .89 75 N 32 P 62 K 94.5Y 41.40 19.85 .91 F test ns ns ns ns Pretransplant Treatment (ppm) 280 N 155 P 94.57 38.35 20.58 .78 280 N 62 P 96.0 42.36 16.68 .95 140 N 155 P 97.3 41.21 18.66 1.18 140 N 62 P 94.7 46.28 19.34 1.27 O N, 0 P 95.8 34.02 24.68 .31 F test ns ns ns ns 2 Each figure is the mean of 5 final nutrient treatments x 3 replications. Y Each figure is the mean of 2 nutrient histories x 3 replications. ns Not Significant 52 In the early planting of experiment 3, the 75 ppm N, 32 ppm P and 63 ppm K nutrient history resulted in a higher marketable fruit yield than the higher nutrient history (Table 14). Treatments in which nutrients were withheld prior to planting had significantly lower marketable fruit yields than adequately fertilized treatments (Table 14). In the late planting, nutrient history and pretransplant treatment did not affect marketable yield (Table 15). Yields of unmarketable fruit (green and cull) were not affected by nutrient treatment in any of the field trials (Table 14 and 15). DISCUSSION Pretransplant fertilization had a significant effect on the nutrient status of tomato seedlings grown in small volume cells. Fertilization of seedlings with N concentrations of 140 or 280 ppm resulted in shoot tissue concentrations of 3.15 to 4.13% total N and .58 to 1.33% soluble nitrate N (Tables 2 and 4). Fertilization with P concentrations of 61 or 155 ppm P resulted in tissue concentrations of .67 to 1.0% total P and .4 to .533 soluble P (Tables 2 and 4). Lorenz and Tyler (12) determined that tissue concentrations of soluble N03-N and PO4-P were good indicators of plant nutrient status. In young tomato plants, a N03-N level in petiole tissue, of .8% is considered deficient and 1.2% is considered sufficient. Soluble P04-P concentrations range from a deficient level of .2% to a sufficient level of .3% (11). In these experiments, the low N treatments may have been insufficient for optimum growth, while P levels were probably not limiting. In treatments in which nutrients were withheld prior to transplanting NO3-N concentration dropped below detectable limits (Table 4). This probably limited the plants ability to reinitiate growth and resulted in poor plant performance. Withholding P fertilizer did not result in as great a decline in tissue total and soluble P concentration. Nutrient levels in shoots of young seedlings would be expected to be higher than those of mature petioles. Concentrations of N and P in petioles of mature plants usually decrease due to remobilization of nutrients to younger plant parts (12). Pretransplant fertilization with nitrogen concentrations of 280 ppm enhanced shoot and root growth after transplanting. Fertilization with 53 54 155 ppm P resulted in slower root and shoot growth compared to lower P concentrations (Table 5, Figure 3). Thus adequate nitrogen nutrition may be the most important factor for rapid regrowth of shoots and regeneration of roots. These results are consistent with those of Tiessen and Carolus (17) who found that N in starter fertilizers stimulated vegetative shoot growth. They also reported that fertilizers which did not contain N severely limited root growth. Gibson and Pill (7) observed that increasing P supply to tomato plants decreased plant dry weight and shoot growth rate. They suggested that increased plant water stress, induced Fe, Mn, or Zn deficiencies or ammonium toxicity may have accounted for the growth reduction. In these studies, rapid early growth of shoot and root tissue was not always a good indicator of high yield potential. Treatments in which nutrients were withheld prior to planting showed a substantial reduction in early growth and had smaller plant size at the time of fruitset. These treatments had lower fruit yields. Treatments which resulted in minor reductions in early growth did not appear to limit the final plant size enough to cause a reduction in fruit yield. These were major differences between the early and late plantings in early shoot and root growth. The late May plantings had greater shoot dry weight and longer root lengths within the first several weeks after planting. Pretransplant nutrition had a greater affect on transplant performance in early' May plantings. In general, pretransplant nutrition did not have a large influence on the performance of transplants which were field set under favorable later season conditions. Controlled environment studies indicated that I - .._ It 55 increasing air and soil temperatures increased shoot and root growth of tomato seedlings. Tiessen and Carolus (16) reported that increasing air and soil temperatures from 50°C to 70°F accelerated the growth of tomato plants. Lingle and Davis (10) also found that increasing soil temperature increased tomato seedling growth and nutrient uptake. They stated that these effects may have been due to increased root metabolic activity and greater water absorption. While temperature is a major factor in more rapid establishment of later plantings, other factors such as higher light intensity and more favorable moisture conditions likely also contributed. Plant nutrient status at transplanting, did not have a consistent influence on the plants ability to absorb soil nutrients following transplanting. However, treatment with the 155 ppm level of P did result in higher total P accumulation in shoots at several sampling times (Table 11). Enhanced nutrient uptake may be due to greater root growth providing increased surface area for nutrient absorption or an increased uptake capacity per unit of root length. Since P fertilization did not promote root growth up to 5 days after transplanting, the higher P concentrations may have affected other biochemical processes which improved nutrient uptake. Other researchers have demonstrated that P uptake is a highly regulated process and that plants adapt to various nutrient environments. Clarkson and Scattergood (5) found that tomato plants which were deprived of phosphorus nutrition, had an increased capacity for phosphorus uptake at the time when visual symptoms of P deficiency appeared. As deficiency symptoms intensified, uptake capacity declined. In this study, although P concentration declined after the seedlings were transplanted, P deficiency symptoms were never visible. ffi‘»u_?fn.m - 1A 0 56 Fertilization during transplant production affected the succulence or tenderness of the seedlings at the time of field setting. Plants which were grown with the 150 N, 64 P, 124 K nutrient history or the 280 ppm N pretransplant treatment were slightly taller and had larger darker green leaves. These plants were noticeably less turgid and wilted more rapidly when the growing media dried out. Plants which were grown at the low nutrient history (75N, 32P, 63K) or fertilized with low N or high P concentrations prior to transplanting, wene more compact, more turgid and did not wilt as rapidly. Plants of the 280 ppm N pretransplant treatment had reduced plant survival (Table 12). Plants which were grown at the higher nutrient history had reduced early growth (Table 6) and lower marketable yields (Table 14). Plants which were subjected to the 155 ppm P treatment had better plant stands (Table 13) and higher marketable yield (Tables 12 and 13). Plants grown at the lower nutrient history tended to have higher shoot dry weights after transplanting (not statistically significant) and higher yields in the early planting (Table 14). Therefore, there appears to be a relationship between factors which result in more tender succulent seedlings, and reduced field performance. Similar responses have been seen in other transplant production systems. Jaworski and Webb (8) found that fertilization of ground bed grown transplants with high rates of nitrogen and low rates of phosphorus resulted in reduced seedling’ storage life, reduced plant stand and lower yield. The detrimental effects of high nutrient history or high N fertilization may be partly due to an increased incidence of transplant shock. Dufault (6) found that muskmelon transplants fertilized with a 250 ppm N, 5 ppm P solution suffered an increased 57 amount of transplant shock and had reduced early yields. As P concentration was raised to 250 ppm N, 125 ppm P, transplant shock was reduced and early yields improved. Traditionally, the practice of withholding fertilizer has been viewed as an acceptable method of hardening transplants (11). However, in this study, treatments in which nutrients were withheld for 10 days prior to transplanting had reduced growth and significantly lower yields (Tables 14 & 15). These plants were visibly stunted at transplanting and were smaller and somewhat chlorotic up to four weeks after planting. These treatments produced less marketable fruit, green fruit and culls. The yield reduction, therefore, appears to be due to a reduced fruit production potential, not to a delay in maturity. Brasher (3) and Weston and Zandstra (18) have also demonstrated that this practice is detrimental to stand establishment and yield. Hardening plants by reducing fertility prior to field setting should never be recommended for transplants grown using plug type systems. One aspect of these studies which is unique is the influence of the small root container on the growth of the tomato plant. The small cell volume restricts root development, which results in a reduced root surface area for water absorption and nutrient uptake after transplanting. With the small cell, shoot development is also limited so the plant has a limited nutrient storage capacity. The smaller shoot also reduces the plants photosynthetic capacity during plant establishment. Therefore, the cultural management of transplants grown in small plugs is thought to be more critical to plant performance than in most other transplant systems. 58 It would be desirable to identify critical tissue nutrient concentrations which result in optimum transplant performance. In these studies, tissue nutrient status at planting was not well correlated with plant performance, within the treatments which were adequately fertilized. Further research should be done to evaluate a wider range of fertilizer nutrient concentrations and establish critical levels for nutrients in the plant tissue. These levels could be used as a guide for growers to adjust fertility programs and to determine the optimum plant condition for transplanting. 'b 10. 11. 12. 13. LITERATURE CITED Adler, P. R. and G. E. Wilcox. 1985. "Rapid perchloric acid digest methods for analysis of major elements in plant tissues." Commun. in Soil Sci. Plant Anal., 16(11):1153-1163. Association of Official Analytical Chemists. 1979. Official methods of Analysis - AOAC. 14th Ed. (Washington D.C.) Brasher, E. it. 1941. Growth and yield of the tomato plant when hardened with certain nutrient solutions. Proc. Amer. Soc. Hort. Sci. 38:629-632. Chapman, PL I). and P. F. Pratt. 1961. “Methods of Analysis for Soils, Plants and Waters. Univ. of California, Division of Agricultural Sciences. Clarkson, 0. T. and C. B. Scattergood. 1982. Growth and phosphate transport in barley and tomato plants during the devel0pment of and recovery from phosphate stress. J. Exp. Bot. 33:865-875. Dufault, R. J. 1986. Influence of nutritional conditioning on muskmelon transplant quality and early yield. J. Amer. Soc. Hort. Sci., 111(5):698-703. Gibson, C. J. and W. G. Pill. 1983. Effects of preplant phosphorus fertilization rate and of nitrate and ammonium liquid feeds on tomato growth in peat-vermiculite. J. Amer. Soc. Hort. Sci., 108(6):1007-1011. Jaworski, C. A. and R. E. Webb. 1966. Influence of nutrition, clipping and storage of tomato transplants on survival and yield. Proc. Fla. State Hort. Soc., 79:216-221. Lachat Instruments Inc. 1986. Operation manual for Lachat Quikchen ion analyser. Mequon Wisconsin. Lingle, J. C. and R. M. Davis. 1959. The influence of soil temperature and phosphorus fertilization on the growth and mineral absorption of tomato seedlings. Proc. Amer. Soc. Hort. Sci. 73:312-322. Lorenz, O. A. and D. N. Maynard. 1980. Knott's Handbook for Vegetable Growers. 2nd edition. (New York: John Wiley and Sons Inc.) Lorenz, O. A. and K. 8. Tyler. 1976. Plant tissue analysis of vegetale crops. p. 21-24 .12. H.M. Reisenauer (ed.) Univ. of California Bull. 1979, Berkeley. Newman, E. I. 1966. “A Method of estimating the total length of root in a sample. J. Appl. Ecol. 3:139-145. 59 14. 15. 16. 17. 18. 60 Nicklow, C. W. and P. A. Minges. 1963. Plant growing factors influencing the field performance of the Fireball tomato variety. Proc. Amer. Soc. Hort. Sci. 81:443-450. Romshe, F. A. 1954. Studies. of plant production methods for vegetable crops: cabbage-tomato-onions-melons and cucumbers. Okla. Bull. 8-421:5-15. Tiessen, H. and R. L. Carolus. 1963. Effects of soluble starter fertilizer and air and soil temperatures on growth and petiole composition of tomato plants. Proc. Amer. Soc. Hort. Sci. 82:403-413. 1963. Tiessen, H. and R. L. Carolus. 1963. Effect of different analyses and concentrations of fertilizer solutions on initial root growth of tomato and tobacco plants. Proc. Amer. Soc. Hort. Sci. 83:680-681. Weston, L. A. and B. H. Zandstra. 1986. Effect of root container size and location of production on growth and yield of tomato transplants. J. Amer. Soc. Hort. Sci. 111(4):498-501. m CHAPTER I I I THE EFFECTS OF PRETRANSPLANT FERTILIZATION 0N NUTRIENT STATUS OF TOMATO SEEDLINGS. ABSTRACT Pretransplant applications of N and P to tomato (Lycggersicon esculentum Mill.) seedlings were evaluated for their effects on plant nutrient status prior to transplanting. Tomato seedlings, cultured in the greenhouse in small volume (2 cm x 2 cm x 2.5 cm) cells were fertilized for 4 weeks with solutions containing 75 or 150 ppm of N, P205 and K20. Prior to transplanting, treatment solutions containing 75, 150, 300 or 450 ppm N and P205 were applied for periods of up to 12 days. Seedling shoot tissue N and P concentrations which ranged from 4.0 to 5.6% N and 1.3 to 1.8% P (dry wt. basis) were enhanced both by the 150 ppm fertilization regime during culture and the high N and P treatment solutions prior to transplanting. Significant increases in tissue N and P concentrations occurred within 3 days of initiation of treatments and increases in total seedling N and P content within 8 days. 61 INTRODUCTION The nutritional status of transplants at field setting time is an important factor influencing stand establishment and the ultimate productivity of the crop. Several studies have indicated that the rates of nitrogen and phosphorus fertilization supplied to seedlings prior to their transfer into the field, influence plant survival, early growth and yield (3,6,8). It has also been demonstrated that the phosphorus concentration of tomato seedling shoots is correlated with rapid early growth and early maturity (14). The uptake of N and P by seedlings is affected by a number of factors. Tiessen and Carolus (15) found that accumulation of N and P in plant tissues was accelerated when the plants were grown at higher air temperatures. The type of phosphorus fertilizer supplied to the plant influences it's nutrient composition (10). Nitrogen form also affects plant nutrient composition. The NH4 form has been demonstrated to increase the plant's ability to absorb phosphate (7). However, the NH4 form of nitrogen can be toxic to the developing plant and the nitrate (N03) form is generally preferred (12). It has also been demonstrated that the media in which the seedling is grown can influence the plants response to N form and it's nutrient composition (11). This study was conducted to determine the influence of fertilization programs on nutrient status of tomato transplants grown in small volume plug trays. The objective was to determine what concentrations of N and P in solutions were necessary to enhance plant nutrient status and how rapidly nutrient status could be changed. 62 MATERIALS AND METHODS This experiment was conducted in the plant research greenhouses at Michigan State University from September to November 1987. Seeds of processing tomato (cv. H2653, H. J. Heinz Co.) were sown in 288 cell plug trays containing Baccto soilless growing media (Michigan Peat 00., Houston, Texas). Following seedling emergence, the plants were subjected to two fertilization regimes. One half the plants were fertilized with a nutrient solution of low concentration (75 ppm N, 32 ppm P, 62 ppm K), while the remaining plants were treated ‘with a solution of higher nutrient concentration (150 ppm N, 64 ppm P, 125 ppm K). These solutions were prepared using Peter's 20-20-20 soluble fertilizer (20N - 8.6P - 16.6K) and deionized water. The nutrient solutions were applied once daily or as the seedlings required watering. Growing temperature was maintained at 18°C night and 24°C day. No supplemental lighting was used. These nutrient regimes were maintained from shortly after seedling emergence until 40 days after seeding. At this time the plants were 13 to 15 cm tall, had 4 to 5 true leaves and were judged to be 7 to 10 days from the stage of development when they normally would be transplanted into the field. The plants of both nutrient treatments were then subjected to a second series of fertilization treatments applied over a 12 day period. The nutrient concentrations applied during this period were: (1) 75 N, 32 P, 62 K; (2) 150 N, 64 P, 125 K; (3) 300 N, 128 P 250 K; (4) 450 N, 194 P, 374 K. These nutrient treatment solutions were also prepared using Peter's 20-20-20 soluble fertilizer and were applied twice daily or as the seedlings required watering. 63 64 The experimental design was a 2 x 4 factorial with the factors: (1) Nutrient History (75 N, 32 P, 64 K or 150 N, 64 P, 125 K) and (2) Final Nutrient treatment (75 N, 150 N, 300 N or 450 N). Plant shoot samples (10 plants) were collected before the start of the final nutrient treatments (0 days) and at 1, 3, 5, 8 and 12 days after the final treatments were initiated. These shoot tissue samples were dried at 60°C in a forced air oven for 3 days. Dry weights were determined and the samples were stored for tissue analysis. The dried plant tissue samples were ground to pass a 20 mesh screen in a Hiley mill. Samples for total N determinations were digested using H2504 (2). Total nitrogen was determined by a Kjeldahl procedure using a Lachat ion analyser (9). Tissue samples for total P analysis were digested using a perchloric acid, hydrogen peroxide digest as described by Adler and Nilcox (1). Total phosphorus was determined colorimetrically using the Fiske-Subarrow method (4). Results were analysed using analysis of variance. Means were separated by least significant difference at the 5% or 1% level. 7"“ 5 RESULTS AND DISCUSSION The tomato seedlings which were cultured with the 150 ppm N, 64 ppm P, 125 ppm K nutrient solution were slightly taller and had larger, darker green leaves at the start of the pretransplant nutrient treatments (40 days after seeding), compared to plants cultured with 75 N, 32 P, and 63 K. These plants had a higher shoot dry weight at 40 days after seeding, (significant at the 10% level) (Table 1). Plants of the two nutrient history treatments had a similar increase in shoot dry during the 12 day pretransplant treatment period and the difference in dry weight was maintained during this period (Table 1, Figure 1). Pretransplant treatment solutions containing relatively high levels of N and P stimulated seedling growth over a 12 day period. Seedlings of all 4 pretransplant treatments had similar increases in shoot dry weight over the first 3 to 5 days after the start of the treatments. Differences between treatments were more obvious at the end of the 12 day period (Table 1). The 300 ppm N, 129 ppm P treatment had a significantly higher shoot dry weight than other treatments (Table 1). The 450 ppm N, 194 ppm P treatment resulted in rapid initial shoot growth which slowed considerably after 3 days. These plants were observed to develop foliar chlorosis and a discoloration of the root tips. This suggests that the high N P concentration was toxic to the young seedlings, possibly due to a salt injury effect. At 12 days, the 75 N, 32 P treatment had the lowest shoot dry weight of the 4 pretransplant treatments (Table 1). Seedlings which were cultured with 150 ppm N and 64 ppm P nutrient solutions had higher shoot tissue concentrations of total N and P at 40 65 —— a ’ 'l 66 Table 1. The influence of fertilization during seedling culture (nutrient history) and pretranSplant nutrient treatments on dry weight of tomato shoots. Shoot dry weight (g/plant) Days after start of treatment Treatment 0 1 3 5 8 12 LSD.01x Nutrient Histor ( m) 75 N 3215 62K .058 .067Y .082 .089 .108 .136 150 N 64 P 125 K .071 .082 .093 .100 .128 .148 F test ns ** ns ns ** ns Pretransplant Treatment (ppm) 75 N 32 P 62 K -- .0742 .089 .092 .117 .128 150 N 64 P 125 K -- .071 .082 .094 .115 .138 300 N 128 P 249 K -- .072 .087 .099 .121 .157 .015 450 N 192 P 374 K -- .078 .093 .093 .120 .145 F test ns ns ns ns * LSD (.05) " - - - .012 x Comparison of means from day 1 to day 12 Y Each figure is the mean of 4 final nutrient treatments x 3 replications 2 Each figure is the mean of 2 nutrient histories x 3 replications “S. *, ** not Significant and significant at the 5 and 1% level 67 Figure 1. The influence of nutrition during tranSplant culture on tomato shoot growth over a 12 day period, after the initiation of pretransplant nutrient treatments. hzmzkdmmk ..._O ._.w_<._.m amt? m><0 75 NF 0— m 0 .v N 0 . _ . L . _ L . e . _ L 0.0 2 Ema nu Ole z 8%. ofl mum . EEEEE.§.E 2 Eco com I 2 Eco 00¢ I fi0.N 1‘. ..N.\ -3 \ 10.0 10.0 (TUDld/N 6w) lNIEIlNOO N 76 rapid growth, and higher shoot dry weights up to a 300 ppm level (Table 1 ) . Total N content in tomato shoots increased in a linear manner over 12 days as fertilizer N increased from 75 to 450 ppm (Figure 3). Seedlings which were fertilized with solutions containing 128 ppm P had higher total P concentration in shoot tissue than seedlings treated with 32 ppm P (Table 3). There were no significant differences in total P concentration between seedlings fertilized with 64, 128 or 192 ppm P. This may indicate that P uptake is a regulated process and that plants can absorb P efficiently from solutions having relatively low P concentrations. It is generally accepted that plants can absorb P from solutions with low P levels, against very large concentration gradients (12). At the 192 ppm P treatment, shoot total P concentration increased over the first 5 days, then decreased. At 12 days after the start of treatments, seedlings treated with 128 ppm P had higher P concentration than those treated with 192 ppm P (Table 3). This suggests that the DTant's ability to absorb P was limited due to the root injury caused by the 450 N, 192 P, 374 K nutrient solution. Phosphorus uptake is an 96121 ve process, requiring carbohydrate metabolism to supply energy (12). If the seedlings were under stress due to a salt injury, the ab? 1 ity of the root to absorb P would be reduced. There were no significant differences in shoot tissue P concentration at day 12 compared to day 1, for any treatment (Table 3). There was a trend to a reduction in P concentration with the 32 ppm P t"eatment, probably due to a growth depletion effect. The 64 and 128 ppm P treatments appeared to supply adequate P to maintain or enhance 1:" Ssue concentrations. h: 77 Total P content in the plant shoots also increased over the 12 day treatment period, although the increase was not as linear as that of total N (Figure 4). Seedlings which were treated with 128 ppm P had a higher P content at day 5 to 12 than those treated with 192 P, due to the reduction in P uptake caused by the salt injury. Nitrogen uptake rate (mg N absorbed per plant per day) increased linearly as N concentration in the treatment solution increased, up to 300 ppm (Figure 5). At 450 ppm N, the uptake rate appeared to level off. Seedlings which were cultured with the high nutrient history (150 N, 64 P, 125 K) had a slightly higher N uptake rate than the low nutrient history plants, probably because they had a higher shoot dry weight. Relative N uptake rate (N uptake per gram of shoot dry weight) decreased from 1 to 12 days after the start of the pretransplant tr‘eatment period (Figure 6). Seedlings which were cultured at the 75 N, 32 P, 62 K nutrient history were more efficient in absorbing N than thOse grown at the 150 N, 64 P, 124 K level. Increasing concentrations of phosphorus in pretransplant treatment 501 utions up to 128 ppm P, resulted in increased P uptake rates (Figure 7) . At a higher P concentration (192 ppm), uptake rate decreased, due to the phytotoxic effect of the 450 N, 192 P, 374 K solution. P uptake rate was the same for seedlings cultured at the high and low nutrient hfStory treatments, despite the larger shoot biomass of the high nutrient history plants. The relative P uptake rate (mg P absorbed per gram of shoot dry ”‘9" ght) also declined from 1 to 12 days after the initiation of the Pr‘etransplant treatments, indicating that as the seedlings grew, they 78 Figure 4. The influence of P concentration in pretransplant nutrient solutions on total P content of tomato shoots over a 12 day treatment period. .: ._.2m_§._.<0 NP OP 0 0 .v N 0 . — . _ p L p b . _ p _ b L ”.0 .._ 0; - \\ N.— - A. i .4; . u 1m... u 10; . ..o.~ n 1N.N i¢.N n. Eco N09 1 . n_ Eaa 0N. «In 10 N egg—nub n— EQQ *0 Elm. . 10 N n. Eon Nn olo 0.0 (lUDld/d 6w) .LNELLNOO d 80 Figure 5. The influence of nitrogen concentration in pretransplant nutrient solutions on N uptake rate of tomato seedlings cultured at two different nutrient levels. 000 20:51.00 2. .0200 2 0m; 06.00 OWN 0m: 0 xwmlemnlzmu 1... 829.23. xnapueeonzofl mum 00.0 10F.0 TON.0 100.0 note 00 .0 (App/iuDId/N 60.1) 3.1318 BMVidfl N 82 Figure 6. The influence of fertility level during transplant culture (nutrient history) on relative N uptake rate (N uptake per gram of shoot dry weight) of tomato seedlings over a 12 day period. : ._.Zm_2._.<0 NP _ OF L w 0 .V N 0 U H 8.29.; . _ . . Xlemanzmh ale 0 O an —ln_.v0lzonp film. I) u I 0 l') (°),M AJp iuo|d 6/N 6w) 31w 3>iVldfl N EINlV'lEiH it culture Iptake 06' a 12 daiv‘ 84 Figure 7. The influence of phosphorus concentration in pretransplant nutrient solutions on P uptake rate of tomato seedlings cultured at two different nutrient levels. 85 29.5400 2_ .0200 n. 0N— . .v0 L 0 2N0lman20N. I 55.22me Teemuzofl min 00.0 10.0 100.0 IN...0 0...0 (App/quold/d 6w) 31W 3)(Vldfl d 86 became less effective in absorbing phosphorus (Figure 8). Seedlings vvhich received daily applications of 32 ppm P during the first 40 days of growth were more efficient in absorbing P than seedlings which received 64 ppm P. This suggests that tomato seedlings may be able to increase their ion uptake capacity to compensate for conditions of limited fertility. Clarkson and Scattergood (5) observed that the Inhosphorus uptake capacity of tomato plants was highest after phosphate supply was discontinued, when the plants were beginning to show deficiency symptoms. This also indicates that low nutrient status Iilants may have a greater ion absorption capacity. This study demonstrates that the nutrient status of tomato seedlings is an important factor determining the plants ability for rapdd growth. The nutrient status of a seedling is very dynamic and can be altered relatively quickly by adjusting the nutrient supply to the plant. Nitrogen status appears to have a greater effect on early seedling growth and is capable of being altered more rapidly than P status. Thus, nitrogen nutrition is a factor which growers can manage, to determine production time and quality of tomato transplants. Nutrient Solutions containing 300 ppm N, 128 ppm P and 249 ppm K applied twice daily, increased the total N concentration of tomato shoots within 5 99.37s. Applications of solutions containing 450 ppm N, 192 ppm P and 374 PDnIK were phytotoxic and reduced seedling growth. Solutions containing a relatively low N concentration (75 ppm) resulted in a gradual depletion of total N in shoot tissue. A fertility level of 150 ppm N, 54 ppm P, 125 ppm K was adequate to maintain N concentration at a Constant level and promote adequate shoot growth. ”In. 87 Figure 8. The influence of fertility level during transplant culture on relative P uptake rate (P uptake per gram of shoot dry weight) of tomato seedlings over a 12 day period. 88 ¢P Hzmfibmmh .._O ._.w_<._.m mm._l._< m><0 N — 0 F 0 0 ¢ N 0 L _ F b L . b . _ . 00.0 me 7.20.2009 film .. u 105.0 a u T00; ., low; flow; 054 ('IM AJp wold 6/d 6w) 31w 3)(Vidfl d HAIR/"138 89 Phosphorus status appears to be more difficult to alter. Shoot tissue total P concentration was not changed significantly by nutrient solutions ranging from 32 to 192 ppm P applied over a 12 day period. This may be explained by the fact that P uptake and accumulation in plant tissue is a highly regulated process (12). Total P concentrations in the plant shoots used in this study were relatively high. If plants having lower P concentrations were used, the nutrient treatments would likely have been more effective in enhancing P status. Several other factors may influence the nutrient status of tomato seedlings, including growing temperatures and light levels. Tiessen and Carolus (15) found that higher air and soil temperatures caused an increase in N and P uptake by tomato plants. Conditions which promote optimum growth are conducive to rapid mineral nutrient uptake (13). This experiment was conducted in the months of October and November, when low light intensities and short photoperiods are not conducive to Optimum growth. If this experiment had been done in the spring the higher light intensities may have promoted more rapid nutrient uptake and greater growth responses. Production of tomato transplants under very favorable growing conditions should result in enhanced nutrient status and optimum plant quality. 1C). 111. 1:2. 12L LITERATURE CITED Adler, P. R. and G. E. Wilcox. 1985. "Rapid perchloric acid digest methods for analysis of major elements in plant tissues." Commun. in Soil Sci. Plant Anal., 16(11):1153-1163. Association of Official Analytical Chemists. 1979. Official methods of Analysis - AOAC. 14th Ed. (Washington D.C.) Brasher, E. P. 1941. Growth and yield of the tomato plant when hardened with certain nutrient solutions. Proc. Amer. Soc. Hort. Sci. 38:629-632. Chapman, H. O. and P. F. Pratt. 1961. "Methods of Analysis for Soils, Plants and Waters. Univ. of California, Division of Agricultural Sciences. Clarkson, 0. T. and C. B. Scattergood. 1982. Growth and phosphate transport in barley and tomato plants during the development of and recovery from phosphate stress. J. Exp. Bot. 33:865-875. Dufault, R. J. 1986. Influence of nutritional conditioning on muskmelon transplant quality and early yield. J. Amer. Soc. Hort. Sci., 111(5):698-703. Gibson, C. J. and W. G. Pill. 1983. Effects of preplant phosphorus fertilization rate and of nitrate and amnonium liquid feeds on tomato growth in peat-vermiculite. J. Amer. Soc. Hort. Sci., 108(6):1007-1011. Jaworski, C. A. and R. E. Webb. 1966. Influence of nutrition, clipping and storage of tomato transplants on survival and yield. Proc. Fla. State Hort. Soc., 79:216-221. Lachat Instruments Inc. 1986. Operation manual for Lachat Quikchen ion analyser. Mequon Wisconsin. Lingle, J. C. and R. M. Davis. 1959. The influence of soil temperature and phosphorus fertilization on the growth and mineral absorption of tomato seedlings. Proc. Amer. Soc. Hort. Sci. 73:312-322. Magalhaes, J. R. and G. E. Wilcox. 1984. Growth, free amino acids and nfineral composition of tomato plants in relation to nitrogen form and growing media. J. Amer. Soc. Hort. Sci. 109(3):406-411. Mengel, K. and E. A. Kirkby 1978. Principles of plant nutrition. (Berne, Switzerland: International Potash Institute). Munson, R. D. 1978. Efficiency of uptake of P and interaction of P with other nutrients. In: Phosphorus for agriculture. (Atlanta, Ga.: Potash/Phosphate Institute). 90 91 14. Pandita, M. L. and W. T. Andrew. 1967. A correlation between phosphorus content of leaf tissue and days to maturity in tomato and lettuce. Proc. Amer. Soc. Hort. Sci. 91:544-549. 15. Tiessen, H. and R. L. Carolus 1963. Effect of soluble starter fertilizer and air and soil temperatures on growth and petiole composition of tomato plants, Proc. Amer. Soc. Hort. Sci. 82:403-413. 1963. SUIflARY These experiments suggest that nitrogen and phosphorus nutrition is a major factor influencing the quality and field performance of plug tray-grown tomato transplants. This is a factor which growers can manage in order to optimize transplant establishment. It is apparent that tomato seedlings respond to favorable environmental conditions, especially warm soil temperatures. In a growth chamber experiment, a 25°C temperature increased shoot growth by 30% and root growth by 500% as compared to a 15°C temperature. However, in field trials, rapid vegetative growth after transplanting was generally not a good indicator of high fruit yield potential. Transplants which were cultured from seedling emergence until 10 days before field setting at a relatively low nutrient regime (75 ppm N, P205 and K20 applied daily) performed better after field setting than plants grown at a 150 ppm level. The low nutrient treatment had a faster shoot growth rate and a 12% higher marketable yield in an early planting. The management of plant nutrition for several days prior to field setting had a dramatic affect on transplant performance. Pretreatments with high rates of N and P for several days before transplanting was found to be an effective method of enhancing nutrient status and plant growth. A 10 day pretreatment duration increased nitrogen and phosphorus concentrations by 12% and 3% respectively over a 5 day pretreatment. The 10 day treatment produced larger seedlings which had a faster growth rate after transplanting. Pretransplant treatment of tomato seedlings with 280 ppm N significantly increased concentration on total N and nitrate in the 92 93 plant, and increased early shoot growth rate following transplanting, but tended to reduce final plant stand. Preplant nitrogen fertilization generally did not affect fruit yield in these studies. A phosphorus pretreatment rate of 155 ppm resulted in total P concentrations in plant shoots at transplanting time ranging from 1.0 to 1.3% while a 62 ppm rate resulted in P concentrations of .7 to .8%. High P nutrition decreased early shoot growth rate but improved final plant stand and marketable yield in an early season planting. Withholding nutrients from seedlings for II) days prior to transplanting reduced tissue concentrations of total N and P, nitrate and soluble P. These low nutrient status plants had a significantly slower shoot growth rate and lower ,yields than plants which were adequately fertilized. I These results contain several interesting trends which may be used in developing fertilization programs for tomato transplants grown in plug trays: (a) The fertilization regime appears to be more critical for transplants which are planted out under stressful, early season conditions. (6) Factors which increase the succulence of seedlings, such as high nutrient levels during transplant culture and high N concentrations are detrimental to transplant performance. These treatments appear to decrease the plant's ability to withstand environmental stress which may in turn result in a reduced ability to set and develOp fruit. (c) Factors such as low nutrient history and high P concentrations resulted in plants which were shorter, thicker and more turgid at (d) (e) 94 planting. These treatments generally resulted in better plant survival, higher nutrient uptake rates and higher yields. While excessively succulent plants should be avoided, plants which are overhardened by limiting nutrient supply are also not satisfactory. This practice causes a depletion of the plant's nutrient reserves and a reduced ability to continue growth and establish its root system rapidly. This stunting of early growth results in a smaller plant which has reduced yield potential. Nutrient concentrations in tomato seedlings tend to be very dynamic. If seedlings are fertilized at low levels during transplant culture, nutrient concentrations decrease over time due to a growth dilution effect. A nutrient concentration of 150 ppm N, and 64 ppm P was adequate to maintain total N and P concentrations at a constant level. A 300 ppm N, 128 ppm P concentration resulted in a gradual increase in tissue N and P level. A 450 ppm N, 192 ppm P concentration damaged the seedlings and reduced nutrient concentration and growth rate. The following guidelines may be useful in developing fertilization programs for processing tomato transplants grown in small volume plug trays. 1. Fertilization should be started soon after seedling emergence. Fertilizer should be applied daily to maintain uniform growth. A fertilizer concentration of about 75 ppm N and P205 should be used. At approximately 10 days before field setting the fertilizer rate should be increased to approximately 150 ppm N and P. The high P concentration is especially important if the seedlings are to be planted in cool soils. 95 3. Do not withhold nutrients before planting in order to "harden off" transplants. 4. If transplants must be held past their scheduled planting date due to adverse field conditions, fertilization should be continued to prevent depletion of nutrient levels. 5. If transplants become deficient in nutrients due to inadequate fertilization before planting, nutrient status can be improved relatively quickly by feeding with 300 ppm N and 128 ppm P. Avoid using higher fertilizer rates as seedling damage may result. A number of questions remain about mineral nutrient effects on tomato transplant establishment. The effects of potassium, calcium, magnesiuni and the micronutrients may be valuable areas for future research. However, while these nutrients are essential for growth it is unlikely that their plant tissue levels have as great an impact on plant establishment as those of nitrogen and phosphorus. However, adequate levels of these elements are necessary in a transplant fertility program to prevent the development of deficiency problems. A number' of' other: cultural factors undoubtedly influence field performance of transplants. The potential use of supplemental lighting and C02 enrichment during transplant production should be investigated. The successful development of processing tomato transplant systems will require integration of all the available knowledge on nutrition, environment and production in order to produce high quality plants to meet the demands of the industry. _‘ H APPENDICES 96 Appendix 1. 97 Climatological Data for field trials (Experiment 1, 2 and 3 ) during transplant establishment EXPERIMENT # 1 (Harrow 1986) Average Average Avg Soil Daily High Daily Low Precip Temp (°C) (°C) (°C) (mm) 10cm depth May 1-10 18.9 7.7 5.0 14.0 May 11-20 20.1 10.9 50.0 15.9 May 21-31 23.7 14.2 21.9 16.5 June 1-10 22.5 12.7 93.3 18.2 June 11-20 23.8 15.9 66.8 19.5 June 21-30 25.1 15.5 4.5 21.4 EXPERIMENT # 2 (Harrow 1987) Average Average Avg Soil Daily High Daily Low Precip Temp (°C) (°C) (°C) (mm) 10cm depth May 1-10 18.8 6.7 15.5 13.4 May 11-20 21.6 10.9 20.2 17.4 May 21-31 26.7 16.0 3.0 21.8 June 1-10 24.3 14.3 53.8 21.0 June 11-20 28.1 17.2 20.0 25.4 June 21-30 26.4 18.1 37.4 23.4 EXPERIMENT # 3 (East Lansing 1987) Average Average Daily High Daily Low Precip (°C) (°C) (mm) May 1-10 18.9 3.6 6.4 May 11-20 23.0 8.1 26.2 May 21-31 26.9 15.0 6.1 June ‘1-10 26.2 13.4 25.6 June 11-20 30.9 16.1 5.6 June 21-30 26.9 15.7 31.8 98 Appendix 2. The influence of pretransplant nutrient treatments on shoot tissue concentration of total N and P, and soluble N03 and PO4-P at transplanting (Harrow 1987). Tissue concentration (% dry wt.) Treatment (ppm) Total N NO3-N Total P Soluble PO4-P Early Planting 280 N 155 P 3.582 .90 1.50 .97 280 N 62 P 3.85 1.04 1.10 .77 140 N 155 P 2.89 .32 1.58 1.06 140 N 62 P 2.79 .24 1.05 .77 F test: N ** ns ** ns P ns ** ns ** Late Planting 280 N 155 P 4.18 1.34 1.90 1.20 280 N 62 P 4.19 1.35 1.45 1.01 140 N 155 P 3.70 .72 1.89 1.27 140 N 62 P 3.55 .87 1.62 1.06 F test: N ** ns ** ns P ns ** ns ** 2 Each figure is the mean of three replications. ns, ** Not significant or significant at the 1% level. 99 Appendix 3-1. The influence of fertilization during seedling culture (nutrient history) and pretransplant nutrient treatments on total N concentrations in tomato shoot tissue during a 12 day treatment period. (Complete data for all treatment combinations). Total N (% of dry weight) Nutrient Pretransplant Days after start of treatment History Treatment (ppm) (ppm) 0 1 3 5 8 12 75 N 32 P 75 N 32 P 4.362 4.19 4.22 4.13 4.02 3.89 150 N 64 P 4.36 4.28 4.21 4.47 4.41 4.41 300 N 128 P 4.36 4.42 4.62 4.87 4.89 4.95 450 N 192 P 4.36 4.43 4.87 5.16 5.30 5.49 150 N 64 P 75 N 32 P 5.05 4.96 4.98 4.92 4.47 4.40 150 N 64 P 5.05 4.96 5.05 5.02 4.87 4.90 300 N 128 P 5.05 4.98 5.19 5.36 5.24 5.28 450 N 192 P 5.05 5.05 5.22 5.51 5.41 5.68 1 Each figure is the mean of three replications. 100 Appendix 3-2. The influence of fertilization during seedling culture (nutrient history) and pretransplant nutrient treatments on total P concentrations in tomato shoot tissue during a 12 day treatment period. (Complete data for all treatment combinations). Total P (% of dry weight) Nutrient Pretransplant Days after start of treatment History Treatment (ppm) (ppm) 0 1 3 5 8 12 75 N 32 P 75 N 32 P 1.542 1.38 1.28 1.29 1.30 1.42 150 N 64 P 1.54 1.38 1.37 1.44 1.45 1.58 300 N 128 P 1.54 1.53 1.55 1.59 1.59 1.64 450 N 192 P 1.54 1.48 1.51 1.63 1.58 1.58 150 N 64 P 75 N 32 P 1.78 1.69 1.71 1.65 1.66 1.51 150 N 64 P 1.78 1.71 1.66 1.64 1.73 1.75 300 N 128 P 1.78 1.76 1.68 1.76 1.80 1.83 450 N 192 P 1.78 1.80 1.71 1.80 1.66 1.67 2 Each figure is the mean of three replications. G N STRTE UNIV 9 (I lllllllllllllllllllllIll”! 930055 I) 112 nICHI (Ml :3 . LIBRARIES lllllllllllllllllllwl 955 E3443