I . IN THE YEAR OF SEEDING PM RESERVES AND“!!! WHO DRY MAITER DISAPPEARANCE 0F 8. ROOT D SPRl'NG-SEEDED ALFALFA YIELD CARBOHYDRATE HERBfiCIDES AND HARVESTED D mm m U M T. m m m... D E M lib-V 1.0 1-: I . if! . . 1W4! i...”.. o... .64.. _ . .otlr 9 J”): - 0...». mm... ....H.7.m.w. .....n.. c4..-ll‘ .’-III 1 .1 I‘w . w.v.-L pic! PUL 1:? r ' if * _' U ; IVERSIETY gree afPh . Thesis for theDe -;MECHIGAN STATE SEPPD 1K . ’ . . l . .a... . n 1.... .0: 0.. gr??? :...»». «fig; .33.. III IIIIII III I||I III III III III II III III IIII II III IIIIII 10187 917 This is to certify that the thesis entitled Yields, root develogment, carbohydrate reserves and In Vitro dry matter diseppearence of Spring seeded alfalfa ( Hedicego setiva L. ) treated with herbicides and harvested in the year of seeding presented by Seppo K. Pulli has been accepted towards fulfillment of the requirements for PhoDo degree in Crop SCience :236Z1?Z;1’ .fiégf ~j2:;;;g§Z/iwr//D Major professor D... gym/2f, /¢7.‘3 07639 I V'fi'n 414:4..1. Michigan State I [Iniversq i(J “Mite-Iii; . sw‘ A ..~‘. r.‘ , I, {l {- hmomc av ‘9 HUAG & SDNS' BUCK BINDERY INC. LIBRARY BINDEWS 8Phllfll'llLllCHIGnn .. -- 31 ABSTRACT YIELDS, ROOT DEVELOPMENT, CARBOHYDRATE RESERVES AND £2_Vitro DRY MATTER DISAPPEARANCE OF SPRING-SEEDED ALFALFA (MEDICAGO SATIVA L.) TREATED WITH HERBICIDES AND HARVESTED IN THE YEAR OF SEEDING BY Seppo K. Pulli The effects of early and late spring-seeding on two varieties of alfalfa treated with a herbicide and seeded at seven rates and given two cutting systems were evaluated in seeding-year yields, population density, root development, total nonstructural carbohydrates in roots, in_vi££g_dry matter disappearance of forage, and incidence of £2132: phthora megasperma Drechs root rot in experiments in 1971 and 1972 at East Lansing, Michigan. Yields in the year after seeding were used to compare the yield levels and in_vitrg_dry matter disappearance of spring seedings with summer seedings in the year after seeding. Yields of alfalfa in the seeding year were reduced when spring seeding was delayed from the earliest possible date in the spring until 3 to 4 weeks later. The highest yield in both experi- ments was obtained from early-seeded alfalfa out three times during the seeding year. Levels of total nonstructural carbohydrates in Seppo K. Pulli the fall of the seeding year and similar yields the next year indicated no differential effect of the cutting systems. Irrigation decreased seeding-year yields when compared to nonirrigation in a year of abovevnormal rainfall, primarily because of a marked incidence of Phytophthora root rot, especially in the late- seeded alfalfa out three times. Saranac yielded more than the Vernal variety in the year of seeding when seeded early. Yields of both varieties in the seeding year increased up to a seeding rate of 9.0 kg/ha when the seeding was early and weed control was satisfactory but a rate of 13.5 kg/ha was necessary for maximum yields in the seeding year when weed control was unsatisfactory and the time of seeding was delayed. Yields in the year after seeding from spring-seeded, herbicide- treated alfalfa were similar to early- and medium-dates of summer seed- ing. Required seeding rates for maximum yield in the year after seeding were 9.0 kg/ha in both spring and summer seedings. Plant population in the fall of the first and second year after seeding was significantly higher in the early seeding than in the late seeding. Cutting either variety two or three times had no significant effects on the number of plants/m2 in the fall of the cutting year or in the second year. The number of plants/m2 at the 9.0 kg/ha seeding rate which produced the maximum yield was 268 over all treatments of cutting date and seeding date in 1971 and 211 at the optimum rate of 13.5 kg/ha in 1972. Higher seeding rates of 18.0 or 36.0 kg/ha produced lower survival of seedlings with the late seeding or with Saranac in contrast to late seeding or the Vernal variety. Seppo K. Pulli Weight per root and total root yields at the end of the seed- ing year were influenced more by population density than seeding time. Over three-fourths of the weight per root in the spring of the year after seeding were in the top 30 cm; 14.6% were in the 30— to 60—cm zone and 6.6% were in the 60- to 90-cm zone. Cutting alfalfa two or three times in the seeding year had no differential effect on weight per root or root yield in the fall of the first and second year. Root yield was constant and paralleled top growth for any seeding rate beyond that necessary to produce maximum forage yield. Seeding-year levels of total nonstructural carbohydrates were very similar or showed only a slight decrease in both varieties, cutting systems, and seeding dates as seeding rates increased from 1.1 to 36.0 kg/ha. Percentages of total nonstructural carbohydrates in roots of seedlings increased gradually in successive cuttings during the seeding year. Irrigation, variety, and seeding rate had no effect on dry matter disappearance of the seeding year forage of alfalfa. The 3- cutting system produced higher in_yi££9_dry matter disappearance values and in_vi£rg_digestib1e dry matter yields than the Z-cutting system in the seeding year. The decrease in dry matter disappearance per day in July was 0.5% in the early seeding and 0.28% in the late seeding. Summer seedings and spring seedings produced similar per- centages of in_!i££2 dry matter disappearance in the year after seed- ing except fer the late—summer seeding which had higher values in the first and second cuttings. Seppo K. Pulli Irrigation increased the incidence of Phytophthora root rot in alfalfa roots when the natural precipitation between April 1 and October 31 was 56 cm, 4.5 cm above normal. Both varieties were generally similar in susceptibility to Phytophthora root rot except that Saranac under irrigation showed somewhat greater susceptibility. Alfalfa seeded at the lower seeding rates of 2.2 and 4.5 kg/ha and irrigated was significantly less diseased than at the higher seeding rates. Maximum Phytophthora root rot was induced by a combination of stress factors including high moisture levels in the soil, frequent cutting, high seeding rates producing smaller plants, and a susceptible variety. YIELDS, ROOT DEVELOPMENT, CARBOHYDRATE RESERVES AND IB_Vitro DRY MATTER DISAPPEARANCE OF SPRING«SEEDED ALFALFA (MEDIEAGQVSATIVA L.) TREATED WITH HERBICIDES AND HARVESTED IN THE YEAR OF SEEDING BY '\ \« Seppo K€ Pulli A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Crop and Soil Science 1973 ACKNOWLEDGMENTS The author expresses his gratitude to Dr. Milo B. Tesar for making his stay at the Michigan State University a learning experience. His encouragement and his assistance in the research and his guidance during the preparation of this dissertation are greatly appreciated. To the following I wish to express my sincere appreciation and gratitude for their assistance during my graduate program: Dr. D. Penner, Dr. J. C. Shickluna, Dr. R. E. Monroe and Dr. P. G. Murphy for discussions, comments, and criticism and a liberal use of their time. The Kellogg Foundation and Michigan State University for providing the financial aid, making my studies possible. My special thanks to my wife, Pirjo, for the spiritual help and patient understanding during the completion of these graduate studies. ii TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . 1 LITERATURE REVIEW . . . . . . . . . . . . . . . . . . . . . . . 5 Seeding rate requirement and yields . . . . . . . 5 Population and root studies . . . . . . . . . . . . . . . 7 Total nonstructural carbohydrates . . . . . . . . . . . . 9 9 O In vitro dry matter disappearance studies . . . . . . . Phytophthora root rot studies . . . . . . . . . . . . . . . l MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . 11 Field studies . . . . . . . . . . . . . . . . . . . . . . . 11 A. Experiment I, seeded in 1971 . . . . . . . . . . . 11 B. Experiment II, spring seeded in 1972 . . . . . . . 14 Laboratory studies . . . . . . . . . . . . . . . . . . . . 20 A. Total nonstructural carbohydrates . . . . . . . . . 20 B. l§_vitro dry matter dry disappearance . . . . . . . 22 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . 24 I. Yields, population and root studies . . . . . . . . . . 24 A. Seeding year yields . . . . . . . . . . . . . . . 24 B. Yields in the year after seeding . . . . . . . . . 35 C. Population and root studies . . . . . . . . . . . . 42 II. Total nonstructural carbohydrates . . . . . . . . . . 61 III. In vitro dry matter disappearance studies . . . . . . . 65 IV. Phytophthora root rot studies . . . . . . . . . . . . . 73 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . 80 BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . 85 iii LIST OF TABLES Table 1. Seeding-year weed-free yields in metric tons per hectare of early- and late—seeded, herbicide-treated Vernal and Saranac alfalfa seeded at six rates and cut two or three times in 1971 (Exp. I) . . . . . . . . . . . . . . . . . Seeding-year yields in weed-free metric tons per hectare of early- and late-seeded, herbicide-treated Vernal and Saranac alfalfa seeded at seven rates, irrigated or nonirrigated and cut two or three times in 1972 (Exp. II) . .. . . . . . . . Second-year (1972) yields in mt/ha of 1971 spring- seeded herbicide-treated Saranac and Vernal alfalfa seeded at six rates, two seeding dates, out two or three times in the seeding year and four times in 1972 (Exp. I) . . . . . . . . . . . Yields in the year after seeding of Saranac alfalfa, summer-seeded in 1971 at three different dates and six seeding rates and harvested four times in 1972 (Exp. I) . . . . . . . . . . . . . . . . . . . . . Plants per square meter of spring-seeding alfalfa in fall in the year of seeding and in the fall of the year after seeding (Exp. 1) . . . . . . . . . . . Weight per root in grams (15 cm) of alfalfa spring seeded in 1971 and sampled in the fall of the seed— ing year and in the fall the year after seeding (Exp. I) . . . . . . . . . Dry matter yields of roots (15 cm) in metric tons per hectare of spring-seeded alfalfa when sampled in the fall of the seeding year and in the fall year after seeding (Exp. I) . . . . . . . . . . . . . . . iv Page 25 30 36 39 43 46 48 Table Page 8. Relative percentage of plants/m2, g/root, and dry matter (DM) of roots at the first cutting in July or early August and in the fall of the year of seeding and in the fall of the fbllowing year, average of early and late seedings cut two or three times in 1971 (Exp. 1) . . . 49 9. Percentage distribution of roots in the top 90 cm in the spring following the seeding of two varieties seeded at six rates, and two seeding dates and harvested two or three times in the seeding year (Exp. I) . . . . . . . . . 52 10. Plants/m2 of alfalfa spring-seeded in 1972 and sampled in the fall of the seeding year (Exp. II) . . . . . . . . . S4 11. Weight per root in grams (15 cm) of alfalfa, spring- seeded in 1972 and sampled in the fall of the seeding year (Exp. II) . . . . . . . . . . . . . . . . . . . . . S6 12. Dry matter yields of roots (15 cm) in metric tons per hectare of spring-seeded alfalfa when sampled in the fall in the seeding year in 1972 (Exp. II) . . . . . . . . 58 13. Total nonstructural carbohydrates of alfalfa roots in percent dry matter (DM) in 1971 spring seedings sampled in the last cutting and late fall, 1971 (Exp. I) . . . . . 62 14. Percentage total nonstructural carbohydrates in roots of early and late spring-seeded alfalfa seeded at seven seeding rates and cut two or three times in the year of seeding (Exp. 11) . . . . . . . . . . . . . . . . . . . 64 15. Percentage in_vitro dry matter disappearance (IVDMD) of alfalfa varieties in the seeding year as affected by frequency of cutting, date of seeding, and irrigation (Exp. II) . . . . .. . . . . . . . . . . . . . . . . .. . . . 66 16. Dry matter yields (DM) and in vitro digestible dry matter yields (IVDMD) of early- and late- seeded Saranac and Vernal alfalfa at seven seeding rates when cut two or three times in 1972, average of irrigation and no irrigation (Exp. II) . . . . . . . . . . . . . . . . 7O 17. Percentage in vitro dry matter digestibility (IVDMD) in the year after seeding of two alfalfa varieties seeded in the previous spring at six rates and harvested two or three times in the seeding year (Exp. I) . . . . . . . . . 71 Table Page 18. Percentage in_vitro dry matter disappearance (IVDMD) of Saranac alfalfa in the year after establishment in summer at six rates and three seeding dates (Exp. 1) . . 72 19. Percentage distribution in October, 1972 of diseased roots of alfalfa from Phylophthora megasperma evaluated in four classifications on spring-seeded alfalfa given various treatments during the seeding year (Exp. II) . . . . . . . 74 20. Phytophthora disease values in alfalfa roots representing degree of disease in fbur classes in the seeding year fall in 1972 (Exp. II) . . . . . . . . . . . . . . . . . . 76 vi LIST OF FIGURES Figure Herbicide-treated spring seedlings in 1972 (Exp. 11) . Phytophthora root rot symptoms in four classes: (1) healthy plants, (2) slightly to moderate lesions anywhere on the root, (3) severe lesions early in the year with new adventitious roots appearing, (4) wevere lesions, remaining roots 2.5 to 5.0 cm Average seeding year yields of early- and late—seeded alfalfa seeded at six rates and cut two or three times in 1971 (Exp. 1) . . . . . . . . . . . . . . Seeding-year yields in metric tons per hectare of early- and late-seeded alfalfa seeded at seven rates and cut two or three times in 1972 (Exp. 11) Second-year yields of 1971 early and late spring-seeded alfalfa seeded at six rates and cut two or three times in 1971 and four times in the year after seeding in 1972 (Exp. I) . . . . . . . . . . . . . . Average yields of early and late spring-seeded early and medium summer-seeded and late summer-seeded alfalfa at six seeding rates when harvested four times the year after seeding in 1972 . . . . . . . . . . . . . . . Alfalfa roots of five seeding rates from 1.1 to 36.0 kg/ha representing unit area of 0.278 m2 in the first cut on July 20 in 1971 (Exp. 1) Seeding—year total top and root yields, number of plants/m2 and root weight, g/root, of early and late spring-seeded alfalfa at six seeding rates harvested in 1971 (Exp. 1) . . . . . . . . . . . . . . . . . Seeding- ear total top and root yields, number of plants/m and root weight, g/root of early and late spring-seeded alfalfa at six seeding rates harvested in 1972 (Exp. II) . . . . . . . . . . . . . . . vii Page 16 18 28 33 37 40 41 44 59 Figure 10. 11. Page Phytophthora root rot symptoms in alfalfa plant showing wilted or stunted yellowed leaves and severe damage in the root . . . . . . . . . . . . . . . . . . . . . . . . 77 Disease values of early— and late-seeded alfalfa seeded at seven rates and cut two or three times . . . . . . 78 viii INTRODUCTION Alfalfa (Medicago sativa L) has long been accepted as the premier forage crop for ruminant animals in areas where it can be successfully grown. Fortunately, this range of adaptability is wide with relatively few areas in the United States where alfalfa cannot be grown . There has been a continuous increase in the use of alfalfa in both the North Central and Northeastern areas, but the expansion of the acreage from the Western States into the North Central area has been one of the dramatic changes in forage use, Smith (36). At the end of the 19th century very little alfalfa was grown in the North Central area excpet in Kansas and Nebraska. Most of the crop was grown in the Western States. The acreage cut for hay in the North Central area increased to 39% of the total acreage cut for hay in the United States in 1909 and to 44% in 1919, Ahlgren (1). With the increase of the culture of alfalfa in the whole area, the acreage cut for hay increased to 48% of the total acreage in the United States in 1929, to 54% in 1939, to 59% in 1949, to 64% in 1959 and to 67% in 1969, Paulling (28). Over two-thirds of the alfalfa seedings made today in the North Central States are seeded in early spring, usually with oats as a companion crop, Tesar and Jackobs (42). These authors listed some advantages for companion crops: 1. They provide some income from grain or forage for pasture, hay and silage. 2. They help to reduce soil erosion. 3. They help to control annual weeds. Summer and fall seedings have usually been seeded without a companion crop. Summer seedings have recently replaced a portion of spring seedings in oats and nearly all of the spring seedings in the winter wheat in the North Central and Northwestern Regions. Legumes seeded in the fall after September 1 in the northern onenhalf of the North Central states do not have sufficient time to be well estab- lished before winter. Spring seeding without a companion crop using herbicides to control broad-leaved weeds is an alternative to seeding with a small grain companion crop. This method is rather new, having been used since about 1960. The new seeding method, sometimes called "clear seeding," becomes an attractive alternative to seeding with a companion crop, generally oats, if the livestockman has little use for the straw for or if stands of alfalfa are total or partial failures due to competition. The herbicides 2,4—DB applied postemergence and EPTC applied preplanting are used most frequently to control the annual broadleaves weeds. Alfalfa is harvested during the year of seeding and provides income in the year of seeding. There are several economic reasons why alfalfa seeded alone and harvested in the year of seeding may be preferred to with a com- panion crop according to Anderson (3): l. One-year delay in alfalfa production with companion crop. 2. Low value placed on oats by many farmers. 3. High potential yield of alfalfa in the seeding year. Tesar and Jackobs (42) emphasize that the price of hay in many Northeastern States, e.g., $50 per ton in New York compared to $25 in Michigan, indicates that seeding without a companion crop may become more popular in the Northeastern than in the Northcentral states. Establishing a good stand is essential in getting high yields of alfalfa. The seeding rate is one of the factors which is important in the stand establishment. Other factors are seedbed preparation, seeding techniques, time of seeding, competition from weeds, soil fer- tility, soil pH, drainage, insects, and management during the seeding year. The objectives of this investigation were to determine (1) how many plants per unit area are necessary for maximum yield in the year of seeding and the next harvesting year; (2) what is the effect of date of seeding and frequency of harvest during the seeding year on the next year's yield; (3) how do spring seedings with herbicides compare in yield the next year with summer seedings which are a recom— mended practice; and (4) what is the effect of seeding rates on digesti- bility of forage and incidence of Phytophthora megasperma root rot disease. Seeding rate studies were related to different management practices including seeding dates, irrigation practices, cutting fre- quencies, and two varieties. Included in this investigation were determinations on in_vitro dry matter disappearance, root carbohydrate reserves, and comparisons between summer seedings and the second—year yields of spring-seeded alfalfa. The investigations were conducted in 1971 and 1972. LITERATURE REVIEW Seedingrate requirements andgyields Limited research on seeding rate of alfalfa harvested in the year of seeding has been reported. Research results and seeding rate recommendations vary considerably. The recommended seeding rates per hectare based on limited research are: Michigan, 9 kg, Tesar (43); Illinois, 13.5 kg, Graffis (18); New York, 19 kg, Pardee (27); Maine, 11-13.5 kg, Brown and Stafford (6). Tesar (43) compared seeding rates 4.5, 9, 13.5, 18 and 26.5 kg/ha in 1969. No difference in first-year yields were obtained above seeding rates of 4.5 kg/ha. Seedings at higher rates were slightly better in the second year but yield differences were not significant. The date of Graffis (18) in Illinois agree very closely with those ob- tained in Michigan. Pardee (27) in New York obtained an average in- crease of 0.47 tons per hectare in the seeding year for the 20 over the 13.5 kg rate. This advantage continued in the second year. Sund (40) from Wisconsin recommends 13.5 kg/ha as the optimum seeding rate for good seedbeds and 18 kg/ha on poorer seedbeds. Brown and Stafford (6) in limited tests in Maine increased seeding—year yields 1.16 tons per hectare by increasing seed rates from 9 to 18 kg/ha. Moline and Robinson (24) in Nebraska obtained no increase in yields during the first two years by increasing seed rates from 10 to 16.5 kg/ha. Average seeding-year yields from several tests in various states range from 4.0 tons per hectare in Minnesota to 5.8 tons per hectare in Maine in the northern part of the United States and 6.9 tons in the central part of the Corn Belt, (42). Reports of hay yields in tons per hectare from at least two trials per state are: Missouri, 5.1 (29); Wisconsin, 3.1 (32); Nebraska, 3.7 (24); Minnesota, 4.0 (3); Michigan, 5.7 (43); and Illinois, 7.2 (19). Seeding-year yields of alfalfa treated with herbicides are approximately 40 to 60% of maximum yields produced by well—established stands (42). Under less favorable moisture conditions, first-year yields are about 20 to 30% of maximum reported yields. In New York, Seaney (35) reports that plots yielding 9 to 11 tons per hectare in the seeding year yielded 14.5 to 16.8 tons per hectare in the next year. In Illinois, Graffis (18) reported second-year yields were about 14.1 tons per hectare compared to the first-year yields of 7.8 tons per hectare. Very little information is available in regard to cutting frequency in the year of seeding. Graffis (17) in Illinois reported a 30- to 35-day interval to be optimum. In another study, Graffis (18) found no difference between two—and three-cutting treatments. Saranac yielded about 10% more than Vernal when cutting frequency was either 30, 35, or 40 days in New York (35). Summer seedings have been made successfully in late July or August in the Great Lakes States and in the Northeast region. Seeding alfalfa after small grain harvest, especially after wheat, has become popular in the Corn Belt States and New York, Tesar and Jackobs (42). In states where summer seeding is recommended, alfalfa, in the year after seeding, generally yields as well as when spring seeded in oats. Michigan yields in the year after seeding were 15.7 tons per acre when spring seeded in oats compared to 13.9 tons for early-August seedings, Tesar (43). Recommended seeding rates of alfalfa harvested in the year after establishment are 4.5 to 9 kg per hectare in arid areas of the United States, Bolton (5), 9 to 13.5 kg in the humid North Central and Northeastern regions, and 16.5 to 33 kg per hectare in the southern and western areas of the United States, Tesar and Jackobs (42). Population and root studies Numerous factors such as temperature, available moisture, age, and osmotic concentration of the media surrounding the seeds are known to influence germination of alfalfa seed, Bula and Massengale (7). Temperature, light, available soil moisture and nutrients, seed size, and environmental conditions under which seeds matured affect seedling vigor, Pritchett and Nelson (30). Available soil moisture greatly influences growth of alfalfa seedlings. A readily available moisture supply during the seedling stage is important, but excessive moisture reduces soil aeration and may result in a shallow root system and plants with small crowns. In addition, excessive soil moisture may induce seedling damage or loss by increasing pathogens, Bula and Massengale (7). Short photoperiods, antinauxin applications, and decreasing stand density were found to enhance stem production of alfalfa, Cowett and Sprague (11). Competition between plants becomes more prevalent as stand density increases, Clements, Weaver, and Hanson (10). The percentage of total sunlight penetrating through plant canopy has no significant effect on crown development and stem production; stem production per plant was not always closely associa— ted with yield, Cowett and Sprague (11). The amount and distribution of rainfall are among the most important factors in determining the optimum seeding rates, Tesar and Jackobs (42). Other important factors are method of seeding, seedbed preparation, soil type and tilth and purpose of seeding. Brown and Stafford (6) in Maine considered 60% emergence as excellent, 40% as fair, and 20% as poor. As a result of competition, disease, insects, winter injury, and other causes, the number of seedlings surviving the first year is generally in the range of 40 to 50% of the seed sown. Thirty to 35 seedlings from 50 seeds is considered good emergence. Of this number, 20 to 25 would survive the first winter. This number was high enough for maximum yield in the first harvest year after establish- ment, Jackobs and Miller (21). Only limited information pertaining to development of alfalfa roots under natural conditions is available. Lamba, Ahlgren and Muckenhirn (23) observed in field studies that root weight increased steadily during the year of seeding, decreased as the soil became more course-textured, and decreased with increasing depth. More than one- half of the weight was in the surface 20 cm layer. The length of root per unit of dry matter increased considerably in each successive 20 cm layer. In Wisconsin, Sund (40) varied seed rates of Vernal and Sara- nac alfalfa from 4.5 to 36 kg per hectare. Mortality of the plants during the first winter after seeding was high at rates above 20 pounds per acre because roots were small. Total nonstructural carbohydrates Very little information is available in regard to the trends of total nonstructural carbohydrates (TNC) in the year of seeding. There is no published information on TNC levels in roots of alfalfa spring seededzuuitreated with herbicides and cut during the seeding year. Several investigators have indicated that carbohydrate root reserves in well-established alfalfa decline during regrowth as new topgrowth is produced and that the decline continues 2 to 3 weeks under field conditions before reaccumulation occurs, Grandfield (20). The importance of carbohydrates in relation to cold tolerance was examined more than 40 years ago, Steinmetz (39). Garber, g£_al, (16) reported that alfalfa was more susceptible to winter injury when its roots contained low concentrations of carbohydrate reserves. In vitro dry matter disappearance studies Although no reports of in_vi£rg_dry matter disappearance (digestability) of alfalfa in the seeding year were found, a considerable amount is available on alfalfa in the year following seeding, Barnes and Gordon (4). Allinson, Tesar and Thomas (2) using a 6-hour in_vit£2_ dry matter disappearance (IVDMD) technique, found that the overall values of five forages cut one, two, three or four times per season were 13.0, 21.6, 24.9 and 25.4, respectively. 10 Reid g£_§13 (31) in New York found that IVDMD of alfalfa declined about %% per day after May 1. Mowatt gt_al, (25) stated that the digestibility of leaves of alfalfa decreased only slightly as the season progressed. However, the IVDMD of the stems declined rapidly early in the season. Unlike the grasses, the stems of alfalfa never attained as high a digestibility as the leaves at the early growth stage. *Phytophthora root rot studies Phytophthora root rot (Phytophthora megasperma Drechs) was first observed in California in 1952, Ervin (12). The disease was observed in Illinois in 1957 (8), in Ohio, Mississippi and Canada in 1964 (34, 22, 9), in Minnesota in 1967 (13), and in Wisconsin, Iowa, Nebraska and South Dakota during 1971 (14). Phytophthora root rot was reported in Michigan in 1972 (44). The disease is always reported to be associated with heavy, poorly drained soils and heavy rainfall and/or irrigation, Frosheiser (14). It becomes severe when the topsoil remains excessively wet during periods of heavy and continuous rainfall. Rotting of the tap- root may occur to a depth of about 50 cm, Frosheiser (14). If the wet conditions persist, the rot continues until the plants die. The plants are wilted or stunted with yellowed leaves. Identification of Phytophora disease in alfalfa was described by Frosheiser (l4). MATERIALS AND METHODS Field Studies A. Experiment I, seeded in 1971 Experiment I was established on the Michigan State Univer— sity farm in East Lansing in 1971. The soil was a productive, well— drained Hillsdale loam soil with pH 6.8. The seedbed was well pre— pared prior to seeding. Fertilizer was broadcast and incorporated with the soil by disking. Germination was 93% for Saranac and 87% for Vernal. Seeding rates wereadjusted to 100% germination accord- ing to germination and seed weight. Experiment I was composed of two general seeding times-- spring and summer. The spring seedings were harvested in 1971 and in 1972. The summer seedings were harvested first in 1972 when yields of the spring and summer seedings were compared. Spring seedings, 1971 . The specific experimental plan and variables were as follows: 1. Field plan Plot design : split-split-split plot, 4 replications Plot size : 0.9 x 7.8 m Rows : 5 rows per plot, 15 cm apart Drill : nursery planter Fertilization : 0—26-26, 600 kg/ha before seeding Harvest area : .9 x 6.8 m 11 12 2. Variables Seeding times : early seeding - April 10, 1971 : late seeding - May 9, 1971 1971 Cutting frequencies : early seeding, 2 cuttings (July 20, Oct. 1) ~ : late seeding, 2 cuttings (Aug. 3, Oct. 1) : early seeding, 3 cuttings (July 9, Aug. 20, Oct. 27) 1 : late seeding, 3 cuttings (July 20, Aug. 27, Oct. 27) 19.72 : 4 cuttings on June 3, July 20, Aug. 21, Oct. 26 Varieties : Saranac--vigorous, moderately winter- hardy, wilt resistant : Vernal—-1ess vigorous, winterhardy, wilt resistant Seeding rates, kg/ha : 1.1 - 54 seeds per m2 : 2.2 - 108 seeds per m2 4.5 - 216 seeds per m 9.0 - 432 seeds per m : 18.0 - 864 seeds per m2 : 36.0 - 1724 seeds per m2 The early seeding was sprayed with 1.1 kg/ha of 2.4-DB and 1.1 kg/ha dalaponcnlMay 22 when the seedlings were at the 2—trifoliate leaf stage in order to control weeds. A similar treatment was applied to the late seeding on June 12. Because of imperfect control of annual weeds, the late seeding was hand-weeded July 5. Stands were treated with an insecticide to control leafhoppers on August 11 and 25 and September 10. The harvested area was 6.1 m2 per plot. Fresh weight yields were converted to dry matter yields of pure alfalfa. A 1000 g fresh weight sample per plot was oven-dried with forced air for 36 hours at 70 C for percentage dry matter. The weed separation sample size was 1000 grams per plot. All yields of alfalfa and weeds are expressed on a weed-free, dry matter basis based on hand separation of all samples. l 13 Roots were counted and root dry weight determination in the top 15 cm of soil was made in the first cutting in each seeding method and cutting frequency. Root samples were taken on 60 cm per row in a total of three directed sampling areas per plot in four replicates. Roots were counted, dry weight determined, and saved for total non- structural carbohydrate (TNC) analysis after the last harvest on October 2 in the Zecutting and on October 27 in the 3-cutting treat- ments. Samples of 15 to 20 roots for late fall determinations of TNC were dug on November 26 for all treatments. Roots were washed in tap water after digging, top growth removed at the junction of the stem and root, trimmed to a length of 15 cm, and dried for one hour in a forced air drier at 100 C to stop enzymatic action. Drying was com- pleted at 70° C for 23 hours and samples ground to pass a 0.6 m sieve, and redried at 700 C befOre analysis. In order to determine dry matter distribution of roots in the soil, roots were sampled in the top 90 cm of soil on April 10, 1972, the year after seeding. A tractor—powered hydraulic soil sampler with a 10-cm diameter tube 152 cm long was used to obtain three 30-cm root sections. Samples consisted of two cores per plot for each of three replicates. All roots were washed and dried for 24 hours at 700 C. Root weights were reported as dry matter. Summer seedings, 1971 Summer seedings were made in three of the four replicates described in the spring seedings. Seeding establishment was similar 14 in all respects to spring seedings except for the following differ— ences: Seeding dates early - July 31, 1971 medium - August 13, 1971 late - August 27, 1971 Variety Saranac only Broadleaved weeds were controlled with 1.1 kg/ha of 2,4-DB one month after seeding. No harvests were made in 1971 on these seed- ings in contrast to 1971 spring seedings which were harvested in 1971. The year after seeding was the first harvest year. Yields are reported on a weed-free, dry matter basis. Determinations in 1972 on 1971 seedings In the spring of 1972, in the year after seeding, plots were fertilized with 700 kg/ha 0-14-42. Four cuttings were made on June 3, July 20, August 21 and October 26. Insects were controlled with insec- ticide on June 4, June 20, July 10, July 24, and August 25. Roots were counted and dry weights determined on October 28 in the spring-seeded plots only. The sample size was the same as in the seeding year. Dry matter yields, percent weeds, and dry weights of roots were determined as in the seeding year. B. Experiment 11 spring sgeded in 1972 Experiment 11 was established in 1972 about 0.5 km west of experiment I on a well-drained, fertile Conover loam soil with pH 6.8, (Figure 1). Four hundred kg/ha of 0«14-42 fertilizer were band—seeded with the alfalfa. The germination of seed of both varieties was adjusted to 15 100% germination and seeding rates were adjusted as described in Experiment I. The early seeding date was delayed until April 27 due to rainy weather. The split-plot design included seeding dates in the main plot, irrigation treatments in subplots, varieties in sub- subplots, cutting treatments in the next split, and seven seeding rates, completely randomized, in final plots. The seeding rate of 1.1 kg/ha included in Experiment I was omitted but seeding rates of 13.5 and 22.5 kg/ha were added. Irrigated blocks were sprinkler irrigated with 5 cm water on July 28 and August 15. Herbicides were applied to the early seeding on May 27 and to the late seeding on June 16. Stands were sprayed to control leaf— hoppers on June 20, July 10, August 10 and 25. Dry matter yields, percent weeds, and dry weight of roots were determined and are re- ported as in 1971. Roots were sampled in each cutting for determina- tions of TNC during the seeding year. The sample size was 20 roots per plot. Numbers of roots and dry weights of roots in the top 15 cm of soil were sampled in the last cutting in the fall. The sample size as 0.325 m2, a total of two 90-cm lengths of row in two areas per plot in four replicates. Roots used for dry weight determinations were also used for Phytophthora root rot studies. The specific experimental plan and variables were as follows: 1. Field plan Plot design : split-split-split-split plot with four replicates Randomization : complete Plot size : 1.58 x 6.6 m Rows : 9 rows per plot, 17.5 cm apart Drill : fertilizeragrain drill with legume band seeder Figure l. Herbicide-treated spring seedings in 1972 (Exp. II). 17 Fertilization : 400 kg/ha, 0-14-42 at seeding Harvest area : 0.9 x 5.7 m (5 middle rows) 2. Variables Seeding times : early seeding — April 27, 1972 late seeding - May 19, 1972 Irrigation treatments : irrigated, 5 cm each on July 28 and August 15 : nonirrigated. Rainfall was 56 cm between April 1 and October 31 Varieties : Saranac : Vernal Cutting treatments : early seeding, 2 cuttings (Aug. 1, Oct. 10) : late seeding, 2 cuttings (Aug. 4, Oct. 10) early seeding, 3 cuttings (July 18, Aug. 31, Oct. 20) : late seeding, 3 cuttings (July 26, Sept. 6, Oct. 20) Seeding rates, kg/ha : 2.2 - 108 seeds per m2 ' 4 5 - 216 seeds per m2 : 9.0 - 432 seeds per m2 : 13.5 - 648 seeds per m2 : 18 0 - 864 seeds per m2 : 22 5 - 1080 seeds per m2 : 36 0 - 1724 seeds per m2 Disease symptoms observed in September on roots of 1972 spring-seeded alfalfa were caused by Phytophthora megasperma Drechs. Positive identification was made by the Department of Pathology at Michigan State University. Roots were sampled in October, 1972. Samples of 0.325 m2 per plot from each of three replicates were obtained on all combinations of the following: early and late seeding, irrigation and nonirrigation, Vernal and Saranac varieties, two and three cuttings in 1972, and seven seeding rates--2.2, 4.5., 9.0, 13.5, 18.0, 22.5 and 36.0 kg/ha. After washing, the roots were classified into four cetegories, Figure 2, as follows based on a classification reported by Figure 2. Phytophthora root rot symptoms in four classes: (1) healthy plants, (2) slight to moderate lesions anywhere on the root, (3) severe lesions early in the year with new adventitious roots appearing, (4) severe lesions, with remainder of roots 2.5 to 5.0 cm long. 19 20 Barnes g£_al. in the 1972 North Central area alfalfa test reports (Minnesota): 1. No lesions. 2. Slight to moderate lesions, blackish, anywhere on root. 3. (a) Severe lesions, many earlier in year and new adventi- tious roots appearing or above dead area. (b) Roots may be severed. (c) Very likely will live over winter. 4. (a) Severe lesions, roots severed by lesions. (b) Roots mostly 1-2 inches long after severing, some 2-3 inches long. (c) Probably will not survive winter. Classification 5 used in the Minnesota study was dead plants which were not classified in this study since an initial number of plants per unit area was not determined. A disease value representing all four studied disease classi- fications was calculated as follows: — _ ZfiYi y ‘ __2 fi- where y.- disease value representing all four categories fi - number of roots in each of four categories Yi - categories one to four 2 fi - total number of plants in four disease categories Laboratory Studies A. Total nonstructural carbohydrates (TNC) Samples prepared as described earlier were obtained from two replications. Total nonstructural carbohydrates were determined as 21 fellows by using a modified Weinman method as described by Smith (37): A lOO-mg dry matter sample was weighed into 125 ml Erlenmeyer flask. About 15 ml distilled water was added followed by 1 to 2 minutes boil- ing to gelatinize starches. After cooling to room temperature, 10 ml of buffer solution containing three volumes 0.2 N acetic acid solution, two volumes acetic acid solution, and 10 ml 0.5% takadiatase enzyme solution were added to the flasks. The flasks were stoppered and incubated for 44 hours at 38 C. After incubation, the solution was filtered through Whatman No. 1 filter paper and diluted to a volume of 250 ml. The Nelson-Somogyi photometric method (26, 38) was used for determination of reducing sugars. A l-ml aliquot was pipetted into a test tube followed by 1 m1 copper-carbonate—tartrate reagent described by Somogyi (38). Solutions were mixed thoroughly and the test tubes were covered by marbles and boiled for 20 minutes in a waterbath. After cooling to room temperature, 1 ml arsenomolybdate color reagent was added, Nelson (26). When the reaction was complete, the solution was diluted with distilled water to 25 m1 and colorimetric measure- ments made withtiBausch and Lomb colorimeter by using a wavelength of 500 mu. A reagent blank, enzyme blank, and two sugar standards ad- justed to the dilution factor were included in the sugar determination. Calculation formulas used were: TNC mg/ml = Z-L-P- : x a 22 (sugar std 1 OD + sugar std 2 OD) stdl mglml std 2 mgfml ' 2 X x dil. factor sample weighti o\° TNC = 100 where y optical density (OD) of sample b = optical density of enzyme blank a = conversion factor, 00 per mg sugar in ml of solution. B. In vitro dry matter dry disappearance(IVDMD) A two stage in_!i££2_rumen fermentation technique was used to determine the dry matter disappearance (digestability) in alfalfa. Determinations were made on (1) 1971 spring and summer seedings har- vested in 1972 and (2) 1972 spring seedings harvested two or three times in 1972. Representative samples of each treatment were obtained in each of the cuttings in two replicates. After drying at 70(3for 24 hours, samples were ground to pass through a 0.6 mm sieve. The par— tially opened bottled samples were dried for six hours at 70 C prior to analysis. A modified Tilly and Terry (46) in_!itrg_fermentation tech- nique was used. Duplicate samples each about 250 mg in size were weighed into 50-ml centrifuge tubes followed by the addition of two 7.5-ml portions of buffer solution. Between adding the buffer, the contents were mixed to saturate the substrate. The sides of the tube were washed down with the second portion of the buffer. The tubes were incubated at 39 C for 30 minutes before 10 ml of a mixture of 23 equal parts of buffer solution and rumen fluid were added. The tubes were flushed with C02, stoppered immediately with a rubber stopper containing a bunsen valve, and incubated at 39 C for 48 hours. The tubes were gently rotated 2, 4, 20, and 28 hours after initiation of incubation to disperse the forage particles. After 48 hours incubation, all samples were acified by adding 1 ml 6 N HCL to each tube, mixed, and 0.5 ml pepsin solution containing 20 g pepsin (1:10000) in 100 m1 H20 was added. Samples were incubated at 39 C for 48 hours without stoppers. After 48 hours incubation, the contents were filtered through previously dry-weighed Whatman No. 54 filter paper, oven dried for 24 hours, and the dry matter residue was determined, Incubated blanks and a known standard were included in the fermentation process. 12_!i££2_dry matter disappearance (IVDMD) was calculated as follows: 100 x sample wt DM - (residual DM - incubated blank DM) 9: IVDMD° sampIe weight DM The reagents used were a buffer-nutrient solution (Kansas State Buffer) made from part A, which consists of 10.0 g KHZPO + 4 0.5 g MgSO4 7 H20 + 0.5 g NaCl+-0.l g CaC12- 2 H20+-0.5 g Urea dis- solved in 1 liter distilled water and part B including 15.0 g NaZCO3 + 1.0 g NaZS' 9 H20 dissolved in 100 ml distilled water. Just prior to use, 20 ml of solution B was added to 1 liter of prewarmed solution A to obtain pH 6.8. If needed, necessary pH adjustments were made. RESULTS AND DISCUSSION 1. Yields,fiPopulation and Root Studies A. Seeding Year Yields Experiment I Yields of Individual Cuttings Seeding-year yields of spring-seeded alfalfa are presented in Table 1. Weather conditions favoring early-spring seeding were excellent and the seeding was made early permitting an excellent com- parison between early- (April 10) and late- (May 9) seeding dates. Weather and soil conditions were favorable during the summer for high yields. The first cut of the 3-cutting system of alfalfa seeded early on April 10 was harvested on July 9. Yields increased gradually with increasing seeding rates. Saranac yields increased up to the 18-kg/ha rate whereas Vernal yields increased up to the 36-kg rate but the yield increase above 4.5 kg/ha with Vernal and 9.0 kg/ha with Saranac was minor. Saranac yielded 0.19 mt/ha more than Vernal. The first cutting of the 3-cutting system of the late seeding yielded 1.37 mt/ha less than with the early seeding. Yields increased up to the 36-kg/ha seeding rate for Saranac and l8-kg/rate for Vernal. Saranac and Vernal produced similar yields. 24 25 Table 1. Seeding-year weed-free yields in metric tons per hectare of early- and late-seeded, herbicide-treated Vernal and Saranac alfalfa seeded at six rates and cut two or three times in 1971 (Exp. 1). Seefiing 3-Cutting 2-Cutting Avg. Variety rate, cuts kglha Cut 1 Cut 2 Cut 3 Total Cut 1 Cut 2 Total Early Seeding Saranac 1.1 2.22 2.24 1.28 5.74a 1.60 1.85 3.45a 4.60a 2.2 2.60 2.30 1.20 6.09a 3.17 1.90 5.07b 5.58b 4.5 3.76 3.24 1.45 8.45b 3.97 2.40 6.37c 7.41c 9.0 3.93 3.33 1.45 8.71b 4.82 2.35 7.16c 7.93c 18.0 4.46 3.11 1.48 9.05b 4.58 1.85 6.43c 7.74c 36.0. 4.43 3.09 1.36 8.88b 4.55 1.84 6.39c 7.64c Avg 3.58 2.88 1.37 7.82 3.78 2.03 5.81 6.82 Vernal 1.1 1.99 1.76 ~l.05 4.80a 2.03 1.59 3.62a 4.21a 2.2 2.83 2.29 1.14 6.26b 3.12 1.92 5.04b 5.65b 4.5 3.14 2.42 1.15 6.70bc 3.35 1.96 5.31b 6.01b 9.0 3.97 2.67 1.17 7.8lcd 4.64 2.05 6.69c 7.25c 18.0 4.10 2.75 1.15 7.99d 4.89 1.95 6.84c 7.42c 36.0 4.33 2.62 1.04 7.99d 4.68 1.94 6.82c 7.40c Avg. 3.39 2.42 1.11 6.92 3.82 1.50 5.62 6.32 Average, early 3.48 2.65 1.24 7.37 3.80 1.97 5.77 6.57 Late Seeding. Saranac 1.1 1.19 1.73 1.15 4.07a 1.93 1.56 3.49a 3.78a 2.2 1.60 2.27 1.50 5.37b 2.39 1.86 4.25ab 4.81b 4.5 1.78 2.50 1.61 5.89b 2.66 1.80 4.46ab 5.18b 9.0 2.48 2.70 1.68 6.86c 3.19 2.04 5.23bc 6.04c 18.0 2.57 2.54 1.64 6.75c 3.54 2.09 5.63c 6.19c 36.0 2.86 2.37 1.51 6.75c 3.72 1.90 5.62c 6.18c Avg 2.08 2.35 1.51 5.95 2.91 1.88 4.78 5.36 Vernal 1.1 .92 1.81 1.16 3.89a 2.05 1.59 3.63a 3.76a 2.2 1.50 2.13 1.36 4.99a 2.15 1.91 4.06ab 4.52a 4.5 2.25 2.65 1.52 6.42b 3.02 1.80 4.82bc 5.62b 9.0 2.52 2.67 1.47 6.66b 3.39 1.87 5.26c 5.96b 18.0 2.80 2.64 1.43 6.86b 3.57 1.98 5.55c 6.21b 36.0 2.83 2.57 1.42 6.82b 3.64 1.78 5.42c 6.12b Avg. 2.14 2.41 1.39 5.85 2.97 1.82 4.79 5.37 Average, late 2.11 2.38 1.45 5.94 2.94 1.85 4.79 5.35 Average, dates 2.79 2.52 1.35 6.65 3.36 1.91 5.28 5.96 LSD .05, Differences between total yields: 0.66 = cutting treatments; 0.94 = cutting at the same level of date; 0.34 = varieties at the same level of date. Means within columns fer a given variety and for a given seeding date with the same letter are not significantly different. 26 The first cutting of the 2-cut system of the early seeding was harvested on July 20, eleven days later than the first cut of the 3-cutting system. This extra growing time yielded only 0.2 tons more than was obtained eleven days earlier. Leaf loss of the older leaves was observed during the period in the 2-cutting system similar to results reported by Fuess and Tesar (15). Saranac increased in yield up to the seeding rate of 9 kg/ha while Vernal showed a slight increase up to 18 kg/ha. Vernal and Saranac yields were similar. Late-seeded Saranac and Vernal in the 2—cutting system cut for the first-time on August 4 had a growing period 11 days shorter than when seeded early. The average yield of all seeding rates of both varieties was 0.86 tons less than with early seeding. Yields increased up to the seeding rate of 36 kg/ha with both varieties which had similar yields. The greatest differences in yield between seeding rates occurred in the first cutting with both seeding dates as shown above. Small differences were noted between low and high seed rates in the second cutting of the 3-cut system. In the last cutting of the 2- or 3—cut systems, there was practically no difference between seeding rates above the 2.2-kg/ha rate since the few existing plants at this seed rate were large enough to utilize the soil moisture and radiation to a maximum. Plants from the lowest seed rate, however, were not dense enough to equal yields of the alfalfa in the more densely populated plots. 27 Total Seeding Year Yields Combined variety results of seeding year yields, Figure 3, show that alfalfa harvested three times was higher yielding at every seeding rate than when cut twice. Yields of early—seeded alfalfa cut three times during the seeding year, Figure 3, were higher than late seedings at all seed rates. A seeding rate of 9 kg/ha was adequate for the maximum yield in both early and late seedings with either cutting system. Seeding-year yields averaged 1.22 mt/ha (6.57 vs 5.35) more in the early than in the late seeding, Table l. The three-cut system yielded relatively more than the two-cut system in the early than in the late seeding, probably because the more frequent cuttings had longer cutting intervals with early—seeded alfalfa. Varieties reacted similarly to the two cutting systems. Late seeded alfalfa cut three times yielded 26.2% more than when cut twice. Yield differences between 3- and 2-cut systems were similar for the early and late seed- ings, ranging between 24 and 27% increases favoring the 3-cut system. Saranac seeded early and cut three times yielded more than any other treatment, indicating that maximum yield under this relatively new system of alfalfa establishment can be achieved when a combination of management factors--highest yielding variety, early establishment, and an intensive 3-cut system--are utilized. When seeded late or cut two times, the two varieties yielded the same, again indicating that the maximum yield of the potentially highest yielding variety will not be expressed unless management factors of early seeding and intensive cutting are also incorporated into the management program. 28 9.0 _ x 3-cut x E x/ 8.0 _ / x 7.0 _ _ SNé--—-------—EEE—--é L ’ - E 2 cut 2 6.0 _ [9" :o [/0 'o__-______:S!t____oL E x ’ o """" 5.0 _ ,6 I,’ o 2-cut I x x 3-cut ’o — Early =E - - - Late = 4.0 _ LSD.os between 3.0 _ Rates at the same level of date and cut 5 Cuts at the same level of date and rate 11224.5 9.0 18.0 36.0 Seed rate kg/ha Figure 3. Average seeding year yields of early- and late— seeded alfalfa seeded at six rates and cut two or three times in 1971 (Exp. 1). 29 Saranac yielded 13% more than Vernal alfalfa for the average of all seeding rates which is consistent with its 10% greater yield in Michigan, (42). Saranac and Vernal in the early seeding under the 2-cutting system reached the maximum yield level at seed rates of 4.5 and 9.0 kg/ha, respectively. Late-seeded Saranac and Vernal har— vested two or three times increased in yields up to a seeding rate of 9 kg/ha. Experiment 11 Yields of Individual Cuttings A late spring and weed competition attributable to poor weed control characterized spring seedings in 1972, Table 2, with the result that yield levels were considerably lower than in 1971, Tables 1 and 2. The first cut of alfalfa, seeded as early in the spring of 1972 as weather conditions permitted (April 27), and harvested two or three‘ times in the seeding years yielded 0.84 and 0.90 mt/ha less, respec- tively, than in 1971 seedings. First-cut yields of late- and early- seeded alfalfa were 0.17 and 0.98 lower, respectively, in the two-cut system in 1972 than in 1971. Yields in the first cut of early-seeded alfalfa in the 3-cut system increased up to 13.5 to 18.0 kg/ha. Saranac had 53% weeds in the first cutting while Vernal had 42%. When seeded late, the 3-cut treatment increased up to the 13.5-kg/ha seed rate with either variety. 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Nm.~ nov.m vu.~ ~5.~ umm.m nu." en.~ no.~ m.n~ one.» enmv.m nwm.n no~.n ww.~ ~m.~ non.n we. vo.~ vn.~ use.n nn.~ on.~ pn~.v mm. vs.” mm." o.m nmo.n now.~ ao~.n p-.n mm.~ h~.~ avo.~ an. -.~ g». aov.n o~.~ -.~ u~o.~ vm. ma." mm. m.v anm.~ «NH.~ ado.~ amo.~ he.” om. e-.~ Nm. ~o.~ no. acu.~ ~5.~ no." anv.~ an. no. u». ~.~ uncauam any vouauwsuu .u>< one; xnuam Hench N use H «:9 Hence n paw ~ usu u uau deuce ~ you a new "each n uau ~ «no m 950 u . ogx x unavowm ucduusu-~ usauusu-n u:«u»:u-~ ucfluusu-n one: Auouuu> . . 1.38am menu .u>< .n~nuoe unavoom ouaq «sateen sauna .nun .nxmu nun” cu acid» 0.9:» no or» use van vouauuuuuco: no vouuuauuu .oounn eo>ou an cocoon nuacmua oucauam and aneuo> vouaouuuovd "anon .vovoon.oue~ v:- .»—uuo mo ounuooz non nee» cannon ooum.oo¢3 a“ «sued» u-ox-u:«voom .N oqnnh 31 In the first harvest of the 2-cut system in both early and late seedings, the 13.5ukg seed rate appeared to be adequate for maxi- mum yield, although a slight increase in yields beyond this seed rate was observed. Since all treatments were irrigated for the first time on July 28, the irrigation had little or no influence on the yield from the first cuts. In the second cut of the 3—cut system, early- seeded nonirrigated plots produced 0.5 mt/ha more yield than irrigated plots. In late-seeded plots, the yield difference was 0.24 ton in favor of no irrigation. This result can probably be explained by Phytophthora root rot which was severe under irrigation (Part IV). Seeding rates for maximum yield in the second cut averaged 13.5 kg/ha in the early-seeded systems. With late seedings of Saranac, the rates were 9 and 13.5 kg/ha fer irrigated and nonirrigated, respec- tively, while 18 kg/ha produced the maximum yield under both conditions with Vernal. In the last cut of the 2-cutting systems, Saranac yielded slightly more than Vernal with no difference between seeding dates. The second irrigation made on August 15 had no positive effect on yield results because of above normal rainfall in the growing season. The final cut in the 3-cutting system produced a greater yield of 0.40 tons without irrigation for the early seeding and 0.34 tons more for late seeding with no difference between varieties. Early seeding yielded slighly more than late seeding. Seed rates for maximum yield were 9.0 to 13.5 kg/ha. 32 Total seeding year yield Seeding year total yields, Table 2, produced no statistically significant difference between early and late seeding since the experi- mental split-plot design is not precise in measuring differences in the first split which is "dates of seeding." However, the yield difference of 0.66 mt/ha for early over late seeding was large enough to indicate the superiority of early seeding as in Experiment I. Irrigated yielded 0.34 tons less than nonirrigated treatments which will be related to the greater incidence of disease (Part IV). The yield difference favoring three over two cuttings was 0.73 tons for early seeding and 0.52 tons for late seeding, again similar to Experiment I. The average yield of alfalfa cut three times was 13 percent greater than when cut twice, significant at the 1% level. Alfalfa seeded early or late, cut three times or twice, under irrigated or nonirrigated conditions increased in yield up to a rate of 13.5 kg/ha with a few exceptions where the maximum yield was at the 9 kg rate. Combined variety results, Figure 4, illustrate the main con- clusions clearly. Irrigated treatments resulted in lower yields than with no irrigation when the alfalfa was cut three times, a condition which is probably related to greater incidence of Phytophthora root rot which is prevalent under wet soil according to Frosheiser (14). Under irrigation, yields increased up to 13.5 kg/ha of seed with all treat- ments. Three cuttings produced only slightly greater yields than two cuttings. Early seeding produced higher yields than late seeding at rates of 13.5 kg/ha or more. When not irrigated, three cuttings .mHH .mxmu Numa a“ mosfiu omega ho can use use mouMH co>om pm wowoom mwammfim wowoom-opmH was -xaumo mo oumuoo: Mom mcou Oahuoe :H mwaomz amok mewwoom .v ohswwm 2:9. 3a.. Doom. me mwm DWI" 0m. ohm fivmw 06m 0mm 0me 0%" CW QWNW 3a.. .E 33 .o _o>o_ 05mm 05 «a 3:0 1 : 9:43.0me .o .65. 089.053 «ovum . o.- .. u 0am... .....i coozzon madman.— wuztmwlllu 1 .ON :54“ x SYN o t . .o.m w \\A\ nu \ 1 1 . q \\\\ \\ 0‘ e JO” llllllllll OI \\O\\\X mo llohrnmfillsme \ . .. 0.0 .._X llllllll . lllll X IlllX\\. X ”NOR erILXIIIIx\\\\ -Aumv owh<0_mm_u20fl 0920.1”... 34 produced considerably more than two cuttings under both early and late dates of seeding. Yields in most instances increased up to the 13.5 kg/ha-seed rate for both dates of seeding and frequencies of cutting and then showed no further increase. Seeding Year Yields in Experiments I and II The seeding year of 1971 was characterized by an early, favorable spring, while the spring of 1972 was late, rainy and cool. A l7-day delay in the early seeding in 1972 compared to the early seeding date in 1971 produced a lower total average yield of 1.81 mt/ha in 1972. In the late seeding, a lO-day delay from the late—seeding date in 1971 resulted in 1.25 tons less yield in 1972 than in 1971. Saranac's yield reduction due to weed and disease problems was 1.77 mt/ha compared to a 1.30 ton reduction in Vernal. Weeds played an important role in the first cuttings in both years but were extremely competitive in early seedings in 1972 because of poor weed control. In the first experiment in 1971, weeds comprised 24% of the total yield in Saranac in the first cutting. Early—seeded alfalfa had 20% weeds in the first cut of three cuttings and 31% in the first cut of the 2-cut system made later. For the 1972 year, early seedings had 50% weeds in the first cut compared to 36% in late seedings. In Experiment 11, both cutting systems had the same amount of weeds-- 42%. In both experiments Saranac had more weeds than Vernal, 47 versus 38%. The amount of seed required for maximum yield in Experiment I was less than in Experiment II, Tables 1 and 2, primarily because of 35 better seedling emergences and better weed control, earlier seeding favoring alfalfa more than broad-leaved weeds, and no detected Phytophthora root rot which was prevalent in the second experiment. Since there was little difference in the varieties relative to seed rates in Table 1 and 2, an average of the varieties will be used for comparing seeding rates in the two years. In the first experiment, Figure 3, yields increased up to the 9-kg/ha rate and then generally levelled off. Some increase was noted up to the 18—kg rate in two cases. In contrast, yields in the second experiment, Figure 4, increased up to the l8-kg rate with or without irrigation. Yields were higher without irrigation in all comparisons in the second experi- ment. B. Yields in the Year after Seeding, Experiment I Yields in the year after seedings established in regular spring seedings made with oats as a companion crop or seeded alone in summer generally yield equally well the next year, Tesar and Jackobs (42). Yields of summer seedings were compared to spring seedings with herbicides to determine relative yields in the year after seeding. Yields of the spring seedings in Experiment I were obtained in four standard cuttings in the next year. Results are reported in Table 3 and Figure 5. Yields in the year after seeding showed that there was a significantly greater yield of 0.36 mt/ha after early seeding on April 10 compared to seeding late on May 9, Table 3. Most of the difference favoring the early seeding was in the first cutting 36 Table 3. Second-year (1972) yields in nt/ha of 1971 spring-seeded herbicidevtreated Saranac and Vernal alfalfa seeded at six rates, two seeding dates, cut two or three times in the seeding year and four times in 1972 (Exp. 1). Dry Matter, mt/ha Seeding Av Variety Rate Z-Cuttings 3-Cuttings C 3' kg/ha uts Cut 3 Cut 4 Total Cut 1 Cut 2 Cut 3 Cut 4 Total Early Seeding Saranac 1.1 2.35 2.04 12.55a 3.56 4.36 2.44 2.09 12.44a 12.49a 2.2 2.47 2.07 13.09b 4.04 4.96 2.42 2.20 13.62ab 13.35b 4.5 2.98 2.41 15.08c 4.25 5.57 2.91 2.35 15.08c 15.08c 9.0 2.92 2.62 15.54c 4.73 5.34 3.09 2.69 15.85c 15.69c 18.0 2.96 2.65 15.45c 4.48 5.09 2.93 2.53 15.03c lS.24c 36.0 2.90 2.68 15.00c 4.19 4.95 3.04 2.51 14.68bc 14.84c Avg. 2.76 2.41 14.45 4.20 5.04 2.80 2.39 14.45 14.45 Vernal 1.1 3. 4. 2.50 1.29 11.52a 3.63 4.46 2.23 1.72 12.03a ll.78a 2.2 3. 4. 2.38 1.55 12.50ab 4.09 4.50 2.51 1.88 12.97ab 12.74b 4.5 4. 4. 2.37 1.71 13.17bc 4.13 4.97 2.96 1.93 14.00b 13.59c 9.0 4. 4. 2.70 1.97 13.92c 4.40 4.95 2.88 1.94 14.17b 14.05c 18.0 4. 4. 2.60 1.84 13.70bc 4.38 4.69 2.89 1.92 13.88b 13.80c 36.0 4. 4. 2.56 1.80 13.20bc 4.39 4.40 2.91 1.72 13.42b l3.3lbc Avg 4. 4. 2.52 1.70 13.01 4.17 4.66 2.73 1.85 13.41 13.21 Late See ing Saranac 1.1 3. 4. 2.10 1.95 11.21a 3.20 4.81 2.11 1.89 12.02a 11.62a 2.2 3. 4. 2.23 1.98 12.23ab 3.39 4.88 2.40 2.21 12.87ab 12.55b 4.5 3. 4. 2.40 2.24 12.946 3.51 5.20 2.80 2.34 13.86b 13.40b 9.0 4. S. 2.85 2.41 14.77c 4.40 5.36 3.17 2.48 15.42c 15.10c 18.0 4. S. 3.03 2.74 15.27c 4.44 5.44 3.15 2.61 lS.64c 15.46c 36.0 3. 4. 3.08 2.55 14.48c 4.31 5.42 3.14 2.59 15.46c 14.98c Avg 3. 4. 2.62 2.31 13.48 3.88 5.18 2.80 2.35 14.21 13.85 Vernal 1.1 3. 4. 1.89 1.33 10.083 3.57 4.34 2.03 1.73 11.68 10.88a 2.2 3. 4. 2.20 1.79 12.09b 3.74 4.66 2.35 1.77 12.52ab 12.3lb 4.5 3. 4. 2.60 1.83 12.98bc 4.13 5.01 2.57 2.02 12.73ab 13.36c 9.0 3. 4. 2.62 1.95 13.42c 4.21 4.81 2.65 2.15 13.82bc 13.62cd 18.0 3. 4. 2.71 2.01 13.61c 4.45 5.37 2.76 2.28 14.86c 14.24d 36.0 3. 4. 2.62 1.83 13.00bc 4.14 4.80 2.52 2.23 13.696c 13.35cd Avg 4. 2.44 1.79 12.53 4.04 4.83 2.49 2.03 13.58 12.96 Average, Dates, Varieties All 1.1 3. 4. 2.21 1.66 11.343 3.49 4.49 2.20 1.86 12.048 11.698 2.2 3. 4. 2.32 1.85 12.48b 3.81 4.75 2.42 2.02 12.99b 12.74b 4.5 3. 4. 2.59 2.05 13.54c 4.01 5.19 2.81 2.16 14.17c 13.86c 9.0 4. S. 2.78 2.24 14.42d 4.44 5.12 2.95 2.31 14.82d 14.62d 18.0 4. S. 2.82 2.31 14.51d 4.44 5.15 2.93 2.33 14.86d 14.68d 36.0 4. 4. 2.79 2.22 13.92d 4.26 4.98 2.90 2.26 14.3lcd 14.12d Avg. 3. 4. 2.58 2.05 13.37 4.07 .93 2.70 2.16 13.87 13.62 LSD .05 between total yields: cut 0.49. dates, 0.28; cuts, 0.52; varieties, 0.25. Varieties at the same level of date and Means within columns for a given variety and for a given seeding date with the same letter are not significantly different. 150 14.0 _ 1 3.0 12.0 mtlha 110 1 0.0 Figure 5 37 o 2-cutting x 3-cutting Early= E ---— Late = L _ p” ’x ~~~~~~~ /’ ’ —8\NNXL O ’r —————— w / ...... 8E I ,’ L I W ”7’ Rates at'the same level of date and cutI I 0 Cuts at thesame level of date and rate g 1f1é245 9T0 16.0 36.0 Seed rate kg I ha . Second-year yields of 1971 early and late spring- seeded alfalfa seeded at six rates and cut two or three times in 1971 and four times in the year after seeding in 1972 (Exp. I) 38 which was significantly higher in yield than late—seeded alfalfa. Yields in the last three cuttings were similar. Yields in the year after seeding were similar when cut twice or three times in the previous year, Table 3 and Figure 5. A slight increase of 0.1 ton in each of the four cuts of the 3—cut over the 2- cut system indicated no harmful effect of the three cutting system. For the average of all treatments of varieties, seeding dates, and frequency of cutting in the first year, yields in the next year increased up to a seed rate of 9 kg/ha and then levelled off, Table 3 and Figure 5. There was an indication that late seedings were in- creasing in yield up to a seed rate of 18 kg/ha but the increase was not significant, Figure 5. Saranac and Vernal reacted similarly in these residual yields to early and late seeding and two or three cuttings in the seeding year. Saranac yielded 1.07 tons more than Vernal. Early, medium, and late summer seedings established in 1971 were cut four times in 1972. Late seedings yielded 1.3 tons less than early or medium seedings which had nearly identical yields, Table 4. The main advantage in yield of the earlier summer seedings was expressed in the greater yield of the first two cuttings. Late in the year, late-seeded alfalfa equalled early seedings in yield. Total yields increased up to the 9 kg/ha rate, Table 4 and Figure 6, and then levelled off. Spring seeding with herbicides and summer seedings estab- lished at the recommened times in early to mid-August, (39), yielded similarly in the next year, Figure 6, indicating that alfalfa 39 Table 4. Yields in the year after seeding of Saranac alfalfa, summer-seeded in 1971 at three different dates and six seeding rates and harvested four times in 1972 (Exp. 1). Seeding DM, mt/ha Rate kg/ha Cut 1 Cut 2 Cut 3 Cut 4 Total Barly_Seedingfi(July 31) 1.1 2.09 3.21 1.73 1.23 8.26a 2.2 2.57 3.60 2.29 1.60 10.06a 4.5 3.57 4.88 2.63 2.15 13.24b 9.0 4.13 5.13 2.90 2.48 14.64bc 18.0 5.08 4.94 2.99 2.47 15.49c 36.0 4.61 5.15 3.13 2.34 15.23c Avg. 3.67 4786 2.61 2.05 12.83 Medium Seeding (Aug. 13) 1.1 1.96 3.63 2.23 1.63 9.47a 2.2 2.49 3.98 2.29 1.80 10.57a 4.5 3.36 4.96 2.57 2.25 13.13b 9.0 3.51 5.10 2.80 2.45 13.86bc 18.0 4.14 5.30 3.12 2.34 14.19bc 36.0 4.22 5.34 3.23 2.57 15.37c Avg. 3.28 4.72 2.78 2.17 12.88 Late Seeding (Aug. 27) 1.1 1.49 2.78 1.92 1.61 7.81a 2.2 2.32 3.78 2.37 2.04 10.51b 4.5 2.43 4.12 2.62 2.18 11.34b 9.0 3.61 4.58 2.63 2.46 13.28c 18.0 3.38 4.52 2.64 2.59 13.13c 36.0 2.88 4.67 2.90 2.67 13.14c Avg. 2.68 4.88 2.51 2.26 11.54 Average,_SeedinggDates 1.1 1.85 3.21 1.97 1.49 8.51a 2.2 2.46 3.79 2.32 1.82 10.38b 4.5 3.12 4.65 2.61 2.19 12.57c 9.0 3.75 4.94 2.78 2.46 13.93d 18.0 4.20 4.92 2.92 2.47 14.51d 36.0 3.90 5.06 3.09 2.53 14.58d Avg. 3.21 4.43 2.62 2.16 12.41 LSD .05 between totals: dates NS. Means within column for a given variety and for a given seed— ing date with the same letter are not significantly different. 40 160. 150. EAB LY_3."9—""-E—°—“-’M ’ " "‘ """ SPRING SEED ING 1‘Cfl ,r / LATE 130. ,P -------------------------- -o 2 / A.1EK)L 1’ I / g , , 11(2L s/I/p 100+ ‘ EARLYand LATE SPRING SEEDING In --x-- EARLYand MEDIUM SUMMER SEEDING 5104.} --o-- LATE SUMMER SEEDING : 8.0. I o z? 1122 4‘5 9'0 160 3‘66 Seed rate kglha Figure 6. Average yields of early and late spring-seeded early and medium summer-seeded and late summer-seeded alfalfa at six seeding rates when harvested four times the year after seeding in 1972. 41 established by the new system of treating spring seedings with herbi- cides with no companion crop is not injured appreciably by cutting in the seeding year. Furthermore, cutting three times in the seeding year is not appreciably more severe on the alfalfa than cutting twice. The maximum production in the year after seeding was obtained at the 9—kg/ha rate for both spring and summer seedings, Figure 7. Alfalfa roots of five seeding rates from 1.1 to 36.0 kg/ha representing unit area of 0.278 m2 in the first cut on July 20 in 1971 (Exp. 1). 42 C. Population and Root Studies Experiment I Plants per unit area in the seeding year Studies were conducted in the fall of 1971 to observe the above—below ground relationships of alfalfa in the seeding year and in the year after seeding. Results are presented in Table 5 and Figure 8. Cutting two or three times had no significant effect on the number of alfalfa plants/m2 in the fall of the cuttings. There was a significant difference, however, between the early seeding with an average of 351 plants/m2 and the late seeding (216 plants). This dif- ference was likely due to a better seedling emergence and a higher per- cent of establishment with the early seedings. Vernal had more plants in the fall but this may have been due, again, to a higher percent of establishment since the number of viable seeds planted per unit area as the same within any seed rate. A significant interaction showed that Saranac with higher seeding rates of 18 or 36 kg/ha had a lower survival of seedlings between first cutting and fall sampling than Vernal. A similar inter- action was found between seeding dates and rates, 1.8., higher seeding rates of 18 or 36 kg/ha produced a lower survival of seedlings in the late seeding than in the early seeding. This detrimental effect was not evident with lower seeding rates. 43 Table 5. Plants per square meter of spring-seeding alfalfa in fall in the year of seeding and in the fall of the year after seeding (Exp. 1). m Cuttings per Year Seeding . Variety Rate 3“CUt Z'CUt Average kg/ha Fall Fall Fall Fall Fall Fall % 1971 1972 1971 1972 1971 1972 72/71 Early Seeding Saranac 1.1 40 40 39 39 40 40 100 2.2 88 80 82 70 85 75 88 4.5 174 168 151 93 163 131 80 9.0 362 253 285 178 324 216 67 18.0 595 217 557 273 576 245 42 36.0 790 325 872 312 831 319 38 Avg. 342 181 331. 181 337 171 58.7 Vernal 1.1 44 31 52 35 48 33 69 2.2 85 80 98 98 95 84 88 4.5 172 142 159 134 172 138 80 9.0 335 239 318 201 327 220 67 18.0 531 285 608 269 570 277 48 36.0 979 295 996 406 988 351 35 Avg. 358 179 372 181 385’ 185 58.6 Average, early 350 180 352 176 351 178 51 Late'Seeding Saranac 1.1 30 27 36 32 33 30 61 2.2 47 31 67 40 S7 35 61 4.5 89 92 114 92 102 92 90 9.0 219 113 177 120 198 117 59 18.0 418 235 324 225 371 230 61 36.0 452 240 423 238 438 239 54 Avg. 288 123' 198 125 288 124 62.0 Vernal 1.1 31 27 26 26 29 27 93 2.2 53 50 50 47 52 46 74 4.5 99 92 133 114 116 103 89 9.0 205 159 243 212 224 186 83 18.0 307 234 398 221 353 228 64 36.0 610 297 596 248 603 273 45 Avg. 228 142 248 145 231 143' 61.9 Average, late 215 131 216 135 216 133 62 Average, dates 283 156 284 156 284 156 S4 LSD'Eetween: . 1971 1972 Dates 116.5* 38.7** Cuts NS NS. Varieties 26.7* 18.5* 44 ear x x _ _ ,‘E 7.01. x/ TOPS 50+ / ”.0 -------- '0 --------- ~ --------- 0L .0" £40.60 3‘” /"i;56'f§"'”x XE 2.0./x ,-O ------- O -------------------- 0L ,...0" E- Early 11 ‘°-°'° LsLate o 112124.15 a?) fee 38.6 f E-Earlyx L-Late o 8001 b " e N s . .0 \1 c. \ 16' v. ‘4 \ 14- ‘10 18 “3 w “1‘ \ 1 '8’ 9 Seed rate kglha Q. X ”as” 7“ S v””’ 200). ~ :1 .10 x ’x \ ygei ht/roo /.O’ R—'Q'T““'! ---------- o . fix 1 1 1 1 l 11 2.2 4.5 9.0 18.0 35-0 Seed rate kglha Figure 8. Seeding year total top and root yields, number of plants/m and root weight, g/root, of early and late spring-seeded alfalfa at six seeding rates harvested in 1971 (Exp. 1). 45 The number of plants/m2 increased as the seed rate increased linearly up to the 9 kg/ha rate and then linearly to the 36—kg/ha rate, Figure 8. As an average of early and late seedings, there were about 40 plants at the 1.1-kg/ha rate with increasing numbers to 877 plants/m2 at the 36—kg/ha rate, Figure 7. The number of plants/m2 at the 9 kg/ha seed— ing rate which produced the maximum forage yield was 268 over all treatments of cutting and seeding date, Figure 8. This number was adequate for maximum yield in the seeding year with both early and late seedings. Accurate correlations of numbers of plants of early and late seedings with yields is not possible since the length of the growing period favored the early seeding which, in fact, was signifi- cantly higher in yield than late seedings as shown earlier in Table 1. The reduction in root number between the earliest sampling in the first cutting in July and the end of the season after the last cutting was similar for early and late seedings, Table 8 and Figure 8. Early seedings had 89% and late seedings had 78% as many seedings in late October as in the first cutting, Table 8. Decreases in root num- ber were 7% at the 1.1 kg seeding rate for all treatments and 18% at the 36-kg rate. 'Weight per root in the seeding year The weight in grams/root is presented in Table 6 and Figure 8. As the number of plants per unit area increased with increasing seed rates, weight per root dropped in both sampling dates. Early seeding resulted in greater emergence than late seeding but the weight per root in the late seeding was equal or higher to that in the early seeding, Table 6. Weight per root in grams (15 cm) of alfalfa spring seeded in 1971 and sampled in the fall of the seed- ing year and in the fall the year after seeding (Exp. 1). Cuttings per Year Seeding 3-Cutting Z-Cutting Average Cuts Variety Rate kg/ha Fall Fall Fall Fall Fall Fall 1971 1972 1971 1972 1971 1972 —Oct.'26_7 Oct. 26 Early Seeding Saranac 1.1 3.95 6.50 2.56 6.57 3.26 6.54 2.2 2.53 4.83 1.80 5.41 2.17 5.12 4.5 1.58 3.15 1.66 3.37 1.62 3.26 9.0 .87 1.72 .98 2.24 .93 1.98 18.0 .60 2.04 .57 1.62 .59 l 83 36.0 .41 1.34 .39 1.56 .40 1.45 Avg. 1.55 3.25 1.33 3.45 1.50 3.36 Vernal 1.1 3.01 7.64 3.13 6.87 3.07 7.26 2.2 2.27 4.08 2.02 4.03 2.24 4.21 4.5 1.29 2.75 1.40 2.50 1.35 2.63 9.0 .84 1.70 .95 1.65 .90 1.68 18.0 .57 1.67 .59 1.38 .58 1.53 36.0 .38 1.27 .37 1.07 .38 1.17 Avg. 1.39 3.19 1.41 2.92 1.42 3.88 Average, early 1.53 3.22 1.37 3.19 1.46 3.20 Late Seedin Saranac 1.1 3.64 6.41 3.88 7.89 3.36 7.15 2.2 2.53 6.93 2.41 4.86 2.47 5.90 4.5 1.63 3.74 1.52 4.25 1.58 4.00 9.0 .98 3.07 1.00 3.10 .99 3.09 18.0 .70 2.06 .70 2.14 .70 2.10 36.0 .65 2.05 .54 1.71 .60 1.88 Avg. 1.59 4184 1.54 3.99 1.52 4.82 Vernal 1.1 3.80 6.38 2.92 5.76 3.05 6.07 2.2 2.86 6.25 2.98 6.12 2.92 6.19 4.5 1.69 4.19 1.62 3.91 1.66 4.05 9.0 1.39 2.70 1.01 2.06 1.20 2.38 18.0 .84 1.75 .69 1 95 .77 1.85 36.0 .54 1.39 .51 1.62 .53 1.51 Avg 1.85 3.78 l. 3.57 1.69 3.68 Average, late 1.77 3.91 1.58 .78 .6 3.85 Average, dates 1.65 3.58 1.48 3.49 1.56 3.54 LSD—between: 1971 2 Dates NS 54* Cuts .17* Varieties NS 47 Figure 8, probably because of less competition for moisture and nutri- ents. A comparison of the average weight per root at the time of the first cutting in July or early August over all levels of cutting, varieties, and cutting frequency with the fall weight shows a three— fbld increase from 0.50 to 1.56 grams per root, Table 8. In a similar comparison of seeding rates, roots from low seed rates increased four- fold in weights whereas the increase was only doubled at the highest seed rate indicating increasing competition with higher seed rates. Root yields in the seeding year Root yields per unit area are presented in Table 7. The root yields were influenced more by the number of plants per unit area than by the weight per root, which was similar for all treatments except seeding rates. Accordingly, early seeding produced signifi— cantly higher root yields than did the late seeding primarily because of larger populations. No significant difference in root yields between Vernal and Saranac was observed. Fewer plants in late seed- ings at the higher seeding rates of 18 and 36 kg/ha, Table 7, resulted in less total root production. Root yields in the 2- and 3-cutting systems were the same. Total root weights doubled between mid-summer and fall at the 36-kg rate but showed a four-fold increase at the 1.1 kg rate, Table 8. 48 Table 7. Dry matter yields of roots (15 cm) in metric tons per hectare of spring-seeded alfalfa when sampled in the fall of the seeding year and in the fall year after seeding (Exp. 1). Cuttings per Year Seeding Variety Rate '3-Cutting 2—Cutting Average Cuts kg/ha Fall Fa11’ Fall *Fa11 F511 F311 1971 1972 1971 1972 1971 1972 E§r1y Seeding Saranac 1.1 1.60 2.74 .96 2.57 1.28 2.66 2.2 2.11 3.77 1.81 3.81 1.50 3.85 4.5 2.72 3.86 2.39 3.20 2.56 3.53 9.0 3.08 4.32 2.79 3.70 2.94 4.01 18.0 3.51 4.03 3.03 4.41 3.27 4.22 36.0 3.11 4.32 3.20 4.53 3.16 4.43 Avg. 2.59 3.84 2.31 3.71 2.58 3.77 Vernal 1.1 1.35 2.42 1.60 2.43 1.48 2.43 2.2 1.94 3.26 1.98 3.90 1.96 3.58 4.5 2.20 3.53 2.13 3.10 2.17 3.32 '9.0 2.80 3.81 2.84 3.06 2.82 3.44 18.0 3.00 3.98 3.04 3.65 3.02 3.81 36.0 3.70 3.98 3.62 4.06 3.66 4.02 Avg. 2.58 3.58 2.52 3.48 2.55 3.45 Average, early 2.60 3.67 2.47 3.56 2.53 3.61 Late Seeding Saranac 1.1 1.07 1.75 1.05 2.50 1.06 2.13 2.2 1.18 2.03 1.39 3.04 1.29 2.54 4.5 1.68 2.94 1.56 3.74 1.62 3.34 9.0 2.08 3.15 1.63 3.45 1.86 3.30 18.0 2.60 4.71 1.92 4.46 2.26 4.59 36.0 2.52 4.91 2.08 4.02 2.30 4.47 Avg. 1.78 3.81 1.51 3.53 1.78 3.48 Vernal 1.1 1.24 2.60 .72 2.27 .98 2.44 2.2 1.27 3.20 1.28 2.82 1.27 3.01 4.5 1.50 3.74 1.75 3.64 1.63 3.69 9.0 2.02 3.87 2.41 4.32 2.22 4.10 18.0 2.46 3.87 2.35 4.15 2.41 4.01 36.0 2.48 3.98 2.72 3.97 2.60 3.98 Avg. 1.83 3.54 1.87 3.53 l. 3.54 Average, late 1.81 3.68 1.74 3.53 1.78 3.62 Average, dates 2.21 3.68 2.11 3.54 2.16 3.62 _LSD between: 1971 1972 Dates .59** N5 Cuts .16* NS Varieties NS NS Table 8. 49 Relative percentage of plants/m2, g/root, and dry matter (DM) of roots at the first cutting in July or early August and in the fall of the year of seed- ing and in the fall of the following year, average of early and late seedings cut two or three times in 1971 (Exp. m I). *— fl 2 Seeding Plants/m g/root DM roots fiaffia Cut 1 Fall Fall Cut 1 Fall Fall Cut 1 Fall Fall g 1971 1971 1972 1971 1971 1972 1971 1971 1972 Saranac 1.1 100 90 88 100 404 834 100 337 774 2.2 100 93 72 100 314 744 100 287 589 4.5 100 82 70 100 291 660 100 275 453 9.0 100 96 61 100 253 668 100 247 377 18.0 100 88 44 100 237 726 100 240 383 36.0 100 78 34 100 250 830 100 186 305 Vernal 1.1 100 96 77 100 364 793 100 473 938 2.2 100 97 88 100 374 754 100 245 500 4.5 100 94 78 100 278 619 100 243 449 9.0 100 86 64 100 269 521 100 233 349 18.0 100 85 46 100 212 528 100 182 262 36.0 100 85 33 100 242 705 100 193 247 Average 1.1 100 93 82 100 383 813 100 429 864 2.2 100 96 83 100 340 744 100 263 540 4.5 100 88 74 100 287 644 100 260 451 9.0 100 91 62 100 263 600 100 241 364 18.0 100 86 45 100 220 607 100 208 314 36.0 100 82 34 100 240 750 100 190 274 Avg 100 85 46 100 312 708 100 236 389 50 Root distribution after first year Alfalfa roots were sampled with a hydraulically operated tractor mounted soil core sampler (lO-cm diameter) in the spring fol- lowing the seeding year to determine the distribution of roots in various seeding-year treatments. Data are presented in Table 9. The main observation was that roots were concentrated mostly in the upper 30 cm which contained 79% of the total dry matter of the roots. Fifteen percent were in the 30- to 60-cm zone, and 7% in the 60- to 90-cm zone. The vertical distribution of roots was more evenly distributed in early than in late seedings. This was probably result of the more advanced growth stage and the better-developed root system of the early seedings. The same trend was found in a variety compari- son which showed that Vernal had more evenly distributed yields of roots all the way down to 90 cm in both early and late seeding. This observation can be due partly to the denser population of Vernal. There was no difference in root distribution between 2- and 3—cutting systems. Lower seeding rates had a more uniform root distribution in the upper 90 cm of soil than higher seeding rates in which the main part of the root dry matter was in the top 30 cm. For example, the average root distribution at the 1.1-kg/ha rate were 73, 18 and 9% in the 0- to 30-, 31- to 60-, and 61- to 90-cm zones, and 82, 13 and 4%, respectively, at the 36-kg rate. This indicates that alfalfa seeded at lower seed rates may have deeper roots than at higher seed rates but this was not confirmed except that every few roots were found below the 90-cm zone one year after establishment in any treatment. 51 Year after seeding density and root studies Root density results in the fall of the year after seeding are presented in Tables 5 and 8. Roots were sampled in the fall of the second year to observe the residual effects of the seeding year treatments and the development of roots during the second year when the plants were harvested four times. The main observation in these plant density studies was that 3-cuttings did not hurt the plants during the seeding year since the number of the surviving plants in the fall of the second year was similar between 2 and 3 cuttings. The trend between seeding dates, observed in the fall of the seeding year, continued in the fall of the second harvest year since the number of plants in early seedings was significantly higher than in late seedings. Early seedings had 51% and late seedings had 62% as many plants as at the time of the first cutting in the previous year, Table 5. Reduction in plant density was greatest at the highest seeding rates and was lowest at lowest seeding rates during the first winter and second growing season. This is shown by comparing plant numbers in the first cutting of the previous year where seedings at the 1.1-kg/ha rate had 81% as many plants as at the 36-kg rate which had only 46% as many plants as in the fall of the second year, Table 8. Results on weight per root in the year after seeding are presented in Tables 6 and 8. As a result of a lower plant density in the seeding year, roots in the late seeding (3.68 g/root) were signi- ficantly larger than roots in the early seeding (3.08 g/root) in the 52 Table 9. Percentage distribution of roots in the top 90 cm in the spring following the seeding year of two varieties seeded at six rates, and two seeding dates and harvested two or three times in the seeding year (Exp. 1). Seeaing ‘348ut 2-8utg Avg. Cuttings Variety Rate cm bglow root crown kg/ha 0-30 31-60 61-90 9:88 31-60 61-90 0-30 31—60 61-90 Early Seedigg_ Saranac 1.1 73.7 14.7 11.6 79.4 14.2 6.4 76.6 14.5 9.0 2.2 75.3 12.9 11.8 79.0 14.3 6.7 77.2 13.6 9.3 4.5 76.6 13.3 10.1 78.2 12.2 9.6 77.4 12.8 9.8 9.0 82.9 13.4 3.7 78.5 12.7 8.8 80.7 13.1 6.5 18.0 82.7 13.8 3.5 78.7 13.7 7.6 80.7 13.8 5.6 36.0 83.9 12.6 3.5 79.4 14.8 5.8 81.7 13.7 111 Avg 7'9'."'2 "-13.5 "7'."'8 78.9 1377' 7.4 79.1 13.6 7.3 Vernal 1.1 69.7 22.1 8.2 70.9 18.9 10.2 70.3 20.5 9.2 2.2 71.1 21.1 7.8 70.6 18.4 11.0 70.9 19.8 9.3 4.5 76.5 17.2 6.3 75.1 18.1 6.8 75.8 17.7 6.6 9.0 78.4 16.0 5.6 77.0 16.3 6.7 77.7 16.2 6.2 18.0 79.6 15.0 5.4 78.3 16.0 5.7 79.0 15.5 5.6 36.0 80.2 14.5 5.3 79.9 15.7 4.4 80.1 15.1 8;8_ Avg 75.9 17.7 6.4 75.3 17.2 7.5 75.6 17.5 6.9 Late Seeding_ Saranac 1.1 76.0 13.1 10.9 70.4 20.9 8.7 73.2 17.0 9.8 2.2 82.3 10.6 7.; 81.7 11.2 7.1 82.0 10.9 7.1 4.5 82.0 12.2 5., 82.0 12.4 5.6 82.0 12.3 5.7 9.0 82.0 12.4 5.7 82.0 12.9 5.1 82.0 12.6 5.4 18.0 83.1 12.9 4.0 83.1 12.5 4.4 83.1 12.7 4.2 36.0 84.6 13.7 1.6 83.9 11.7 4.4 84.3 12.7 8851 Avg 81.7 12.5 5.9 80.5 13.6 5.9 81.1 13.0 5.9 Vernal 1.1 76.2 17.2 6.6 69.9 20.7 9.4 73.1 19.0 8.0 2.2 78.8 14.6 6.6 76.8 13.7 9.5 77.8 1432 8.0 4.5 80.3 15.0 4.7 78.1 12.3 9.6 79.2 13.7 7.1 9.0 82.0 13.6 4.4 79.1 13.4 7.5 80.6 13.5 5.9 18.0 82.6 13.2 4.2 81.6 12.4 6.0 82.1 12.8 5.1 36.0 83.8 12.5 3.7 83.3 16.8 4.9 83.6 12.2 112 Avg 80.6 14.4 5.0 78.1 14.1 7.8 79.4 14.2 6.4 flerggg, seed ng dates and variities Avg. , date, cgt, varim Average 1.1 73.9 16.8 9.3 72.7 18.7 8.6 73.2 17.8 9.0 2.2 76.9 14.8 8.3 77.0 14.4 8.6 77.0 14.6 8.4 4.5 78.9 14.4 ‘6.7 78.4 13.8 7.9 78.6 14.1 7.3 9.0 81.3 13.9 4.8 79.2 13.8 7.0 80.3 13.9 6.0 18.0 82.0 13.7 4.3 80.4 13.7 5.9 81.2 13.7 5.1 36.0 83.1 13.3 3.6 81.6 13.5 4.9 82.4 13.4 848‘ Avg. 79.4 14.5 ’6.1 78.2 14.7 7.1 78.8 14.6 6.6 53 fall of the second year. Neither varieties nor different cutting systems in the seeding year produced any differences in the weight per root in the second year. In seeding rate comparisons, Table 8, the lower seeding rates doubled the root size during the second growing season and, at the higher seeding rates, the increase was three times that observed in the first fall. The decrease in weight per root with fewer numbers of roots and increasing seeding rates is shown by the 1.1-kg/ha seeding rate which had roots four times as heavy as at the 36-kg rate. Yields of roots in the fall of the second year are presented in Tables 7 and 8. There were no significant differences between varieties, seeding dates, or cutting frequencies in the seeding year on root yields in the following year. The root yields followed the trend fbund with top yields, both showing marked increases in produc- tion up to the 9-kg/ha rate and then levelling off. Root yields, however, increased gradually up to the maximum seeding rate of 36 kg/ha while forage yields in the first year increased only to the 9-kg rate. Experiment 11 Plant density data determined in the fall of the seeding year 1972 in Experiment II are presented in Table 10. As a result of a late spring, a growing season with above normal rainfall, and heavy weed competition, the reduction in plant density during the seeding year was considerably higher than in 1971. 54 Table 10. Plants/m2 of alfalfa spring-seeded in 1972 and sampled in the fall of the seeding year (Exp. 11). Seeding Irrigated Nonirrigated Ave. Variety Rate Cutt- kg/ha 3-Cut Z-Cut 3-Cut Z-Cut ings Early Seeding Saranac 2.2 38 46 23 27 34 4.5 54 92 81 S8 71 9.0 125 102 119 119 116 13.5 132 200 182 189 175 18. 222 233 227 274 240 22.5 314 320 338 321 324 36.0 455 405 517 490 467 Avg. T97 799 717' 7T7 793 Vernal 2.2 39 41 35 36 38 4.5 109 93 73 81 89 9.0 130 138 135 163 142 13.5 201 213 208 229 213 18.0 311 314 304 301 307 22.5 415 341 313 422 373 36.0 506 624 544 478 538 Avg. 7?? 797 737 7?? 713 Average, early 219 226 222 228 223 Late Seedigg Saranac 2.2 39 39 26 48 38 4.5 70 61 74 88 73 9.0 163 135 158 171 157 13.5 212 175 223 232 210 18.0 193 242 265 283 246 22.5 298 253 401 350 325 36.0 363 485 396 502 188 Avg. T97 T99 779 739 212 Vernal 2.2 43 36 35 32 37 4.5 92 78 83 102 89 9.0 172 155 159 209 174 13.5 203 185 255 340 246 18.0 324 317 328 388 339 22.5 314 413 335 438 375 36.0 382 474 603 534 489 Avg. 779 737 757 797 771 Average, late 205 218 239 266 232 Average, dates 212 222 231 247 228 LSDhbetween: Dates = NS} Irrigations = N3; varieties, 27.979*; Cuttings = 15.4*. 55 The stand density in early- and late-seeded stands was similar. The reduction in stand density of Saranac was significantly higher than with Vernal when compared to the amount of seed planted. This was more evident when Saranac was irrigated and heavily infested with Phytophthora root rot. As in Experiment I, there was no difference in the effect of cutting systems on plant population in the fall of the year, Table 10. The reduction in plant density was slightly higher when the early- seeded stand was irrigated and significantly higher when the late seeding was irrigated. Plant density was much higher at the higher seeding rates, Table 10, especially in the late seeding. Irrigated treatments with high seeding rates were significantly lower at the 5% level than in nonirrigated plots. All these diffierences can be partly related to the disease problem to be discussed later. Weights per root of spring seedings in Experiment 11 are presented in Table 11. Seeding dates and irrigation treatments did not produce any significant differences in weight of individual roots. Saranac had heavier roots than Vernal which was likely the result of fewer plants per unit area. Roots were heavier at the 1% level in the 2- than in the 3-cut system. This can be partly a result of Phytophthora disease, but probably mostly the result of later planting dates in 1972 result- ing in harvest periods shorter than necessary for three cuttings. Weights per root decreased markedly from low to high seed rates with a five-fold decrease between seed rates of 2.2 and 3.6 56 Table 11. Weight per root in grams (15 cm) of alfalfa, spring- seeded in 1972 and sampled in the fall of the seeding year (Exp. 11). Seeding Irrigated Nonirrigated Average Variety Rate Cutt- kg/ha 3*Cut Z-Cut 3-Cut Z-Cut ings Eafly‘Seeding Saranac 2.2 1.49 1.79 2.03 2.29 1.90 4.5 1.31 1.16 1.36 1.81 1.41 9.0 .83 1.07 .85 1.15 .98 13.5 .71 .74 .65 .96 .77 18.0 .51 .58 .61 .62 .58 22.5 .48 .56 .46 .52 .51 36.0 .31 .40 .38 .40 .37 Avg .81 .99 .91 1.11 .93 Vernal 2.2 1.28 1.48 1.63 2.06 1.61 4.5 .90 1.06 1.08 1.57 1.18 9.0 .98 .82 .90 1.06 .94 13.5 .52 .95 .58 .81 .72 18.0 .47 .57 .45 .58 .52 22.5 .36 .55 .42 .42 .44 36.0 .27 .38 .32 .37 .34 Avg. .68 .83 .79 .98 .87 Average, early .74 .87 .85 1.04 .88 Late Seedin Saranac 2.2 1.26 2.21 77II 2.47 2.03 4.5 .96 1.68 1.19 1.88 1.43 9.0 .64 .98 .77 .97 .84 13.5 .50 .94 .54 .76 .69 18.0 .47 .81 .52 .72 .63 22.5 .44 .63 .40 .59 .52 36.0 .31 .37 .43 .40 .38 Avg. . 1.09 .86 1.11 .93 Vernal 2.2 1.32 2.17 1.08 2.13 1.67 4.5 .82 1.27 1.03 1.28 1.10 9.0 .62 1.04 .58 .70 .73 13.5 .56 .76 .51 .74 .64 18.0 .43 .60 .45 .47 .49 22.5 .51 .52 .37 .46 .47 36.0 .36 .38 .25 .33 .33 Avg. .66 .96 .61 .87 .77 Average, late .66 1.03 .74 .99 .85 Average, dates .70 .95 .79 1.02 .87 LSD‘between:"Dates = NS; Irrigations = NS; Varieties = .13577; Cuttings = .13***. 57 kg/ha. When irrigated, roots of plants in the lowest seeding rates were considerably smaller than when not irrigated. The total yields of roots in the fall of the year are pre- sented in Table 12. Total yields were similar between early or late seedings, varieties, or irrigation levels. Because seedings were made about two to three weeks later than normal, the 2-cutting system pro- duced significantly higher yields than 3 cuttings. In the seeding rate comparison, root yields increased up to the seeding rate of 13.5 kg/ha, and then leveled off, paralleling yields of top growth which reached a maximum at the same rate, Table 2. Comparisons between Experiment I and Experiment 11 Combined variety and cutting frequency results obtained in the year of seeding in 1971, Figure 8, and in 1972, Figure 9, showed the forage yields and the root yields closely paralleled each other. Both increased up to a seed rate of 9 kg/ha in Experiment I and 13.5 kg in Experiment 11 which had poorer weed control, and, therefore, required more alfalfa plants to produce the maximum yield. Root weight and top growth did not increase above these rates indicating that the number of roots multiplied by root weight is constant for any rate of seeding beyond the maximum yield level. The ratio of top to roots was 164:100 in the first experiment and 338:100 in 1972. In Figure 8, combined variety and cutting frequency results show in Experiment I that the number of plants in the fall was con- siderably higher in the early than late seeding which coincides with higher forage yields from early seeding. In both experiments, plant 58 Table 12. Dry matter yields of roots (15 cm) in metric tons per hectare of spring-seeded alfalfa when sampled in the fall in the seeding year in 1972 (Exp. 11). Seeding Irrigated Nonirrigated Average Variety Rate Cutt— kg/ha 3-Cut Z-Cut 3-Cut Z-Cut ings Early Seeding Saranac 2.2 .50 .87’ .50 .60 .60 4.5 .70 1.06 1. 08 .97 .95 9.0 1.04 1.09 1.00 1.38 1.13 13.5 .93 1.47 1.18 1.65 1.31 18.0 1.14 1.27 1.39 1.70 1.37 22.5 1.41 1.77 1.45 1.65 1.57 36.0 1.44 1.61 1.85 1.84 1.69 Avg. 1.07 1.36 1.70 1.10 1.73 Vernal 2.2 .47 75 .55 .80 .64 4.5 1.00 .99 .85 1.27 1.03 9.0 1.13 1.14 1.21 1.70 1.29 13.5 1.04 1. 56 1.19 1. 78 1.39 18.0 1.43 1. 65 1.52 1. 92 1.63 22.5 1.49 1.81 1.29 1. 73 1.58 36.0 1.36 2.33 1.73 1.73 1.79 Avg. 1.13 1.46 1.19 1.56 1.34 Average, early 1.08 1.38 1.20 1.48 1.28 Late Seedin Saranac 2.2 .48 .84 {1 1.22.76 4.5 .66 1.00.86 1.65 1. 04 9.0 1.02 1.35 1. 20 1.77 1.34 13.5 1.06 1.63 1.21 l. 80 1.42 18.0 .91 1.94 1.35 2. 01 1.56 22.5 1.30 1.58 1.58 2. 04 1.63 36.0 1.20 1.77 1.53 2.00 1.62 Avg. .95 1.44 1.17 1.79 1.34 Vernal 2.2 .55 .91 .46 .65 .64 4.5 .77 .94 .84 1.33 .97 9.0 1.07 1.59 .90 1.39 1.24 13.5 1.10 1.41 1.26 1.92 1.42 18.0 1.38 1.85 1.42 1.79 1.61 22.5 1.56 1.95 1.23 2.01 1.63 36.0 1.31 1.77 1.48 1.81 1.59 Avg. 1.10 1.49 1.09 1.56 1.31 Average, late 1.03 1.47 1.13 1.67 1.33 Average, dates 1.06 1.43 1.17 1.57 1.31 LSD between: Dates = NS; Irrigations = NS; varieties = NS; Cuttings = .15***. 59 L E-Early x' 60 L-Late o x x TQPS x: 5.0. /: ...... o----o -------------- oL .X \ a X ”” EEEKD' ’JD' 6"/ 2 - O /x______x-——: ___g_____5?_o_r§_____gE 1.0 . gfig...”-o“..__..--O"""""' 2'2 435 9.0 15.5 18.0 22.5 360 Seed rate kglha E-Early x x” L'Lat. O / (sit 600. <0 .30 . ,8 3 E 4 a 15400- x 20 a g\ a E \g x a ” czoo_ / ~\ -10 s) --- - . /$7.,// . 6\-~an.._..,.w9ugm(root IE 2.2 4.5 9.0 13.5 180 22.5 36.0 Seed rate kglha Figure 9. Seeding-year total top and root yields, number of plants/m and root weight, g/root of early and late spring-seeded alfalfa at six seeding rates harvested in 1972 (Exp. 11). 60 population increased almost linearly with increases in seed rate. As a result of fewer plants, the weight per root in late seedings was slightly higher than in early seedings at all seeding rates. In Experiment 11, Figure 9, the number of plants surviving in the first fall was much lower than observed in 1971 and this coincided with lower forage yield in 1972 than in 1971. This was probably a result of the later establishment in both seeding dates because of a cool, rainy spring and above-normal rainfall during the growing season which also increased root rot disease on the fine-textured Conover loam soil. The number of plants surviving in the fall was almost identical between early and late seeding and similar to late seeding in 1971. Weight per root in both years was very similar except that lower seeding rates in 1971 had heavier roots than in 1972, probably a result of more favorable growing conditions in the first experiment in 1971. The plant density requirements in the first fall for maximum yield were high in 1971 with 325 plants per m2 at the 9-kg/ha seeding rate in the early seeding and 210 plants in the late seeding. The percent survival in the early seeding from seed planted at the optimum 9-kg/ha rate was 75% which can be considered excellent, Tesar and Jackobs (42), and 49% in the late seeding which is considered good. In the second experiment in 1972, plant density requirements for the maximum yield at 13.5-kg/ha seeding rate were 194 plants m2 in the early seeding and 228 plants m2 in the late seeding. The survival 61 percent of early seeding from the seeds planted was considered poor averaging 28% in the two seeding dates. 11. Total Nonstructural Carbohydrates Experiment I Total nonstructural carbohydrates (TNC) in the fall in roots of alfalfa spring—seeded in 1971 are presented in Table 13. High levels of TNC are generally associated with good survival of older established stands especially in cold climates according to Smith (36). However, there is no published information on TNC levels in spring- seeded alfalfa harvested during the year of seeding. The data in Table 12 show that levels of TNC averaged 44.9% in the roots of the last cutting on October 2 in a 2-cut system. Levels of TNC decreased only slightly—-1.4%--as the seed rate increased from 1.1 to 36 kg/ha. In the 3ucutting system sampled on October 28 in the third cutting, TNC averaged 43.9% compared to 44.9% in the second cutting of the 2—cutting system and were similar in early and late seedings and in the two varieties. As in the 2-cut system, TNC decreased only 1.2% as seed rates increased with very few exceptions. In the late fall on November 26 after fall growth had stopped, roots from both cutting systems were analyzed to observe the effects of seeding year treatments on TNC in roots of alfalfa. Although there was a decline in percent TNC, since the last cuttings in October, TNC levels were high, near 37%. There were no differences in TNC levels attributable to dates of seeding or cutting frequencies so it can be concluded that managing seeding-year alfalfa under a high-yield system 62 Table 13. Total nonstructural carbohydrates of alfalfa roots in percent dry matter (DM) in 1971 spring seedings sampled in the last cutting and late fall, 1971 (Exp. 1). Seealng Cuttingsper Year Variety Rate ‘73lCut ‘77 4“ 2«Cut ‘ Av.’Cut. kg/ha Oct—28 'Nov’26 Oct 2 NOV 26 Nov 267 "Percent Percent *Percent Percent Percent Early Seeding Saranac 1.1 44.5 37.7 4514 38.2 38.0a 2.2 44.3 37.4 45.4 38.5 37.9ab 4.5 44.0 37.0 46.1 38.4 37.7ab 9.0 43.9 36.3 45.6 38.0 37.1bc 18.0 43.7 35.8 44.9 37.7 36.8c 36.0 42.6 35.9 44.6 37.0 36.4c Avg. 43.9 36.6 45.3 38.9 37.3 Vernal 1.1 44.2 37.1 44.9 37.8 37.5a 2.2 44.0 37.0 44.9 37.9 37.4a 4.5 43.9 36.5 45.4 36.7 36.6ab 9.0 43.7 35.9 45.5 36.7 36.3b 18.0 43.6 35.8 45.1 36.4 36.1bc 36.0 43.2 35.0 44.8 35.8 35.4c Avg. 43.8 36.7 45.1 36.9 36.6 Late Seeding Saranac 1.1 44.4 38.6 44.4 37.8 38.2a 2.2 44.2 38.4 44.9 37.7 38.0a 4.5 43.8 37.4 44.8 37.4 37.4ab 9.0 43.7 37.3 45.6 36.2 36.7bc 18.0 43.4 37.1 45.6 36.0 36.5c 36.0 43.4 37.0 44.6 36.0 36.5c Avg. 43.8 37.6 45.1 36.9 37.7 Vernal 1.1 44.3 38.1 44.3 37.5 37.8a 2.2 43.9 37.7 44.5 37.3 37.5ab 4.5 43.8 37.3 45.6 37.3 37.3ab 9.0 43.6 37.0 45.2 36.5 36.7bc 18.0 43.4 36.5 44.1 36.2 36.3c 36.0 43.1 36.2 43.7 35.6 35.9c Avg. 43.7 37.1 44.6 37.9 36.9 Average, date and variety cut:_73%%§%y 1.1 44.3 37.9 44.8 37.8 37.6a 2.2 44.1 37.6 44.9 37.8 37.7a 4.5 43.9 37.0 45.4 37.4 37.2b 9.0 43.7 36.6 45.5 36.8 36.7c 18.0 43.5 36.3 44.9 36.6 36.4cd 36.0 43.1 36.0 44.4 36.1 36.0d Avg. 43.8 36.9 44.9 37.9 36.9 LSD, Nov. 76, between: dafes = NS; Cuts = NS; Varieties = NS. Means with the same letter are not significantly different at .05 level. 63 of early seeding and an intensive 3-cutting harvest system will not injure plants appreciably during the seeding year because the TNC levels in both cuttings systems were equal after fall growth had stopped. The next year's yields were similar in a uniform 4-cut system, Table 3, again indicating there were no residual effects due to any differences in the 2- or 3-cut system in the seeding year. Levels of TNC declined slightly with few exceptions in every variety, cutting system, and date of seeding as seed rates increased from 1.1 to 36 kg/ha. The decline over all treatments was from 37.6 to 36.0% TNC which are levels adequate for excellent winter survival. Experiment 11 Levels of TNC at each cutting and in late fall in roots of alfalfa Springoseeded in Experiment 11 in 1972 are presented in Table 14. Levels of TNC showed that percentages were lowest when sampling began in the first cutting in summer and increased with each succes- sive cutting in both the 2— and 3-cutting systems. There was no difference in TNC levels between early- or late-seeded alfalfa in any cutting in either the two- or three-cut system. Levels of TNC in roots increased from 30.2% in cut 1 to 38.9% in cut 2 to 40.0% in cut 3. Levels in the first cut of the 2-cut system were higher than in the 3-cut system because of an approximately 2-week later sampling date. The first cut of the 2-cut system had 36.0 and the second cut had 44.4% TNC indicating that percent of TNC in roots of seedlings increases gradually during the summer season as 64 4.4.4 42 42 4.5.4 .4.4 544544> 4:4 4444 454453 44444 42 42 42 42 42 4444 454442 44444454> 42 42 42 42 42 44444 4 54 5 4:4 5 54 5 48 5 .54 4 4454444 5 4454444 "4443444 444 4.44 5.44 4.44 4.44 5.44 4.54 5.44 4.44 .w>< 4.44 4.44 4.44 4.44 5.44 5.44 4.44 4.44 H4444> 5.54 4.44 5.44 4.44 4.44 4.44 4.44 4.44 4444544 45 444 .4 444 5.44 5.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 5444 4.44 4.44 4.44 5.44 4.44 4.44 .4>< 4.44 4.44 5.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 5.44 4.44 H4=uo> 4.44 4.44 4.44 5.44 4.44 5.44 5.44 4.44 4.44 4.44 5.44 4.44 4.44 4.44 5.44 4.44 4444544 4 4444 .5 4:4 45 444 .5 444 4.44 4.54 4.44 4.44 5.44 4.45 4.455.4.44 4.44 4.44 4544 5.44 4544 4.44 4.44 5.44 .4>< 4.44 4.54 4.44 4.44 4.44 4.45 4.45 4.45 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 H4444> 4.44 4.54 4.44 |5m44 4.44 4.44 4.45 5.44 5.44 4.44 5.44 4.44 4.44 4.44 4.44 4.44 4444544 45 55:4 .5 4:4 4 4=<-w5 444 .mmwvoom mum; 5. 5.44 5.44 5.44 4.44 5n44 5.54 4.54 4.54 .4>< 4.44 4.44 4.54 5.44 4.44 4.44 4.44 4.44 H4454> 4.54 4.44 4.54 5.54 4.54 5.44 4.44 4.54 4444544 45 444 .4 444 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 4.44 5.44 4.44 5.44 4.44 4.44 .4>< 4.54 5.54 4.54 4.54 4.54 5.44 4.54 4.44 4.44 4.54 4.44 5.44 5.44 4.44 5.44 4.44 H4454> 4.44 4.44 4.44 5.44 4.44 4.44 4.44 5.44 4.44 5.44 5.44 4.44 4.44 4.44 4.44 5.44 4444544 54,444,.5 444 44 444 .5 444 4.44 5.45 4.44 4.44 4.44 4.45 4.45 5.44 4.44 5.44 4.54 4.54 5.54 4.44 4.44 4.44 .4>< 5.44 4.44 4.44 4.54 4.44 4.44 5n44 4.45 4.54 5.54 4.54 4.54 4.54 4.44 4.54 4.44 H4454> 5.45 4.45 4.45 4.45 4.45 4.45 4.44 5.44 4.44 5.44 4.44 4.44 4.4 4.44 4.44 4.44 4444544 44 54:4 45 4:4 4 =4 .4 4:4 .wdwvoom xfihwm nqw>< 4.44 4.55 4.44 4.45 4.4 4.4 5.5 .mm4 4.44 4.55 4.44 4.44 4.4 4.4 5.5 pmmr5 4:444 544444> mmmww opmnwcamoom . .nHH .mxmv mnwvoom mo amok map :4 moswu mounu no o3» use can mopmn mcwwoom co>om pm wovoom 4mHmmHm vowoomsmcfihmm mama and xfinmo mo muoon :4 moumnwxsonhmo H453uoshumco: Hmpou ommpzounom .vfi oHnMH 65 shown by Reynolds (41) and Graber g£_§l, (16) for older established stands of alfalfa. The higher TNC level in the second cut of the 2-cut series (44.4%) as compared to the third cut of the 3-cut series (40.6%) was likely due primarily to the longer interval since the previous cutting. The interval between the last two cuttings in the 2-cut systems averaged 69 days whereas it was only 37 days in the 3-cut systems. Both systems should have adequate levels of carbohydrates for high winter survival since levels of 35% are generally considered adequate fbr high sur- vival, Smith (36). All seven seeding rates in each cutting had similar carbo- hydrate levels with some exceptions where a slightly lower level of TNC might have been the result of Phytophthora disease. Since plant numbers/m2 in the fall of the year averaged 37 plants at the 2.2-kg/ha seeding rate and 482 plants at the 36-kg/ha rate, it is evident that large increases in plant density are not harmful to percent TNC levels in the roots of alfalfa cut two or three times in the seeding year. 111. In Vitro Dry Matter Disappearance Studies Experiment 11 £§_!i£32_dry matter disappearance (IVDMD) of the forage of alfalfa was determined under different frequencies and management practices in the seeding year as an estimate of digestibility by animals. Results are presented in Table 15. A generalized conclusion is that percent IVDMD was a function of age of the plant tissue after seeding or cutting and relative position in the growing season. 66 Table 15. Percentage in vitro dry matter disappearance (IVDMD) of alfalfa varieties in the seeding year as affected by_?requency of cutting, date of seeding, and irrigation (Exp. 11). Early Seeding Late Seeding Seeding Variety Rate 3-Cutting Z-Cutting 3-Cutting Z-Cutting kg/ha ----———-—-— Cut 1 Cut 2 Cut 3 Cut 1 Cut 2 Cut 1 Cut 2 Cut 3 Cut 1 Cut 2 Irrigated (I: Saranac 2.2 72 7 70.8 76.0 66.2 72.2 73.5 74.3 75.8 72.9 72.2 4.5 73 1 72.8 76.8 66.3 72.0 76.1 74.3 76.0 72.3 72.6 9.0 73 3 72.8 76.7 66.2 71.0 75.7 73.4 76.8 72.4 71 7 13.5 73.5 72.4 77.1 66.6 70.5 75.7 73.6 76.2 72.5 71.8 18.0 73.0 72.7 76.1 66.6 71.1 76.0 74.7 76.2 72.5 72.6 22.5 73.9 72.3 76.1 66 9 70.8 75.2 72.8 76.0 72.7 71.8 36.0 74.2 71.8 77.0 67 2 70.8 76.0 73.4 76.3 72.8 72.2 Avg. .373 “-72.4 —76 s 6373' —771. _75.4 _73.8 76.2 T7 .6 72 1 Vernal 2.2 73.4 72 6 75.3 66.1 72.1 73.1 73.0 75.1 70.8 71.5 4.5 74.1 72.9 76.2 65.8 72.3 74.1 73.0 75.0 71.9 71.5 9.0 74.0 73.2 76.4 66.0 72.3 73.9 73.1 75.0 71.5 71.4 13.5 72.8 73.4 76.0 67 5 71.5 74.0 73.7 75.9 71 2 71.4 18.0 72.3 73.2 76.5 65 4 69.7 73.7 73.8 75.3 71.3 70.6 22.5 72.6 72.3 76.5 65 4 70.3 73.6 72.5 75.7 71.4 71.1 36.0 72.4 72.9 75.8 65.7 70.8 73.5 72.8 75.9 71.9 70.2 Avg. 73.6 72.9 76.1 65.7 71 3 73 7 73 1 75 4 71 4 71 1 Avg. I 73.6 72.7 76.3 66.1 71.2 74.6 73.5 75.8 72.0 71.6 Nonirrigated (NI) Saranac 2.2 70.1 72.9 74.9 65.4 71.8 73.3 73.4 75.2 71.3 71.7 4.5 71 S 72.6 76.3 65.7 72.1 73.7 73.0 75.5 71.2 71.3 9.0 71.8 71.1 76.4 65.9 72.0 73.7 73.0 76.7 71.3 71.2 13.5 71.7 72 3 76.7 66.0 72.1 74.0 74.2 76.0 71.6 72.2 18.0 71.9 71.8 76.9 65.9 72.3 74.9 73.7 76.3 71.5 72.2 22.5 71.7 72.3 76.5 66.6 70.9 74.9 73.7 76.6 72.3 71.9 36.0 72.5 71.8 76.6 65.2 70.5 75.4 73 1 7S 9 72.4 71.9 Avg. 71.6 72.1 76.3 65.8 71.7 74.3 73.4 76.0 71.7 71.8 Vernal 2.2 70.3 73.2 76.6 64.2 72.2 72.9 73.8 76.2 70.5 71.9 4.5 70.7 73.2 76.0 64.3 72.5 72.6 73.7 75.9 71.2 70.8 9.0 71.5 73.0 76.6 65.2 70.4 73.9 73.6 75.8 71.2 71.2 13.5 72 7 71.2 76.7 64.5 70.6 74.0 73.8 76.1 71.5 70.5 18.0 72.4 71.5 76.9 64.2 71.0 73.8 73.8 76.1 71.0 70.5 22.5 71.9 71.7 76.9 64.4 70.8 73.1 73.6 76.5 70.9 71.2 36.0 73.0 72.2 76.8 64.3 70.9 72.6 73 0 75 9 71 2 70.9 Avg. 71.8 72.2 76.6 64.4 71.0 73.3 73.6 76.0 71.0 71.0 Avg. N1 71.7 72.2 76.5 p 65.1 71.4 73.8 73.5 76.0 71.4 71.4 Average, varieties and irrigation treatments 2.2 71 5 72.7 75.7 65.5 72.1 73.2 73.6 75.5 71.4 71 8 4.5 72.4 72.9 76.3 65.5 72.3 74.1 73.5 75.6 71.7 71 5 9.0 72.8 72.5 76.5 65.8 71.5 74.3 73.2 76.0 71.6 71 4 13.5 72.9 72.3 76.6 65.7 71.2 74.4 73.8 76.0 71.7 71 5 18.0 72.7 72.3 76.6 65.5 70.6 74.6 73.9 75.9 71.6 71 5 22.5 72.8 72.1 76.5 65.8 70.4 74.2 73.1 76.2 71.8 71 5 36.0 73.2 72.1 76.5 65.6 70.7 74 3 73.1 76.0 72.0 71 3 Avg. 72.6 72.4 76 3 65.6 71.3 74 2 73 5 75 9 71 7 71 5 Avg. 73.8 68.3 74.5 71.6 LSD between: 2-Cutting 3-Cutting Cut 1 Cut 2 Cut 1 Cut 2 Cut 3 Dates .6"' NS NS NS NS Irrigations NS NS NS NS NS Varieties NS NS NS NS NS Rates within dates NS 1.2“ l.5"' NS NS 67 Frequently cut alfalfa in this experiment had a higher IVDMD value in agreement with Allinson 31311.. (2) for 2-year old alfalfa stands in Michigan. The average of all 3-cut systems was 74.2% for the 3-cut system compared to 70.0% for the Z-cut systems, indicating the superiority in quality related to frequent cutting in the seeding year. lg_!i££g_dry matter disappearance was high in both early- and late— seeded alfalfa in this relatively immature forage of seeding-year alfalfa. Late-seeded alfalfa, however, was higher in percent IVDMD than early-seeded alfalfa in both the 3- and 2-cut systems. This is shown by average IVDMD values of 68.3 and 73.8% for early-seeded alfalfa cut two or three times, respectively, and higher values of 71.6 and 74.5% for late—seeded alfalfa cut two or three times. Values of percent IVDMD were in the order of Cut 1 = Cut 2 < Cut 3 for both early and late seedings in the 3-cut system. IVDMD was in the order of Cut 1 < Cut 2 for early seedings and Cut 1 = Cut 2 for late seedings in the 2—cut systems. The decrease in percent IVDMD with age of plant tissue is shown by examining values for alfalfa at different stages of maturity in the first cutting. In the first cutting of the 3-cut system of early seeded alfalfa, IVDMD on July 18 was 72.6% which was 7.0% higher than in the first cutting on August 1 of the 2-cut system. The de- crease in IVDMD during this period of 14 days was 0.50% per day which agrees precisely with the decline in older stands of alfalfa in similar stages of growth in late May to early June as reported by Reid g£_§l_ (31) in New York. 68 In another comparison in this experiment, the first cutting of the 3-cut system of late-seeded alfalfa had an average IVDMD of 74.2% on July 26, 2.5% higher than in first cutting of the 24cut sys- tem on August 4, a period of nine days. The average decline during this period was 0.28%, considerably less than the 0.50% daily decline obtained from early-seeded alfalfa cut under similar 2— and 3-cut systems. The difference may be due to smaller and less mature plants in the later seeding. The shorter interval of 9 compared to 14 days may also have been a contributing reason to the lower daily decline of IVDMD in the later-seeded alfalfa. The IVDMD of the last cuttings of the 2-cut systems made on October 10 were similar-«71.3 and 71.5%, respectively--for the early- and late—cut systems. Likewise, IVDMD in the last cuttings of the 3-cut system on October 20 was similar (76.3 and 75.9%). The IVDMD in the third cutting averaged 4.7% higher than in the second cutting, probably because the plant tissue sampled since the previous cutting was 18 days less mature (68 vs 50 days). The third cutting has a higher percentage of IVDMD (75.9%) than the second cutting of the 3-cut system (73.5%) taken earlier because of a much slower decline in IVDMD in alfalfa in the fall. Slower plant growth due to cooler temperatures and less radiation may have contributed to the slow decline. The first cutting of the 3-cut system of alfalfa seeded early at low rates had a significantly lower IVDMD than at higher rates, probably because the fewer plants at the low seed rate were more mature than when more thickly spaced at higher seeding rates. There were no differences between other seeding rates. LEO-o- “A"; I... 69 Total dry matter yields and total digestible dry matter yields (IVDMD) or feeding value per hectare of early- and late—seeded alfalfa are presented in Table 16. The data show that increases in utilizable feed per acre are a function not only of yield but also of IVDMD and emphasize early seeding and frequent cutting of alfalfa harvested in the year of seeding for maximum production of feeding value. The highest yield of 4.80 mt/ha of dry matter obtained from early-seeded alfalfa out three times had a feeding value per hectare of 3.73 mt which is the product of dry matter in mt/ha multiplied by percent IVDMD. This feeding value was 0.93 mt/ha greater than alfalfa seeded late and cut only twice (2.80 mt/ha). Experiment I Studies on IVDMD were conducted in Experiment I in 1972, a year after the seeding. Both spring and summer seedings were examined in all four cuttings harvested at the same time. The IVDMD results in the year after seeding alfalfa in spring and summer are presented in Tables 17 and 18, respectively. Seeding-year treatments of 3 cuttings and 2 cuttings in early and late seedings did not produce any differences between those treatments in any of the four cuttings harvested in the next year, Table 17. The average IVDMD values in the four harvests were similar to the two cutting systems of the previous year. Comparisons between varieties or seeding rates showed no significant differences. Summer seedings, Table 18, did not show any differences in IVDMD between seeding rates of the previous summer. Late-summer 70 Table 16. Dry matter yields (DM) and in vitro digestible dry matter yields (IVDDM) of‘éarIy- and late- seeded Saranac and Vernal alfalfa at seven seeding rates when cut two or three times in 1972. Average of irrigation and no irrigation (Exp. II). Seeding Early Seeding Late Seeding Rate kg/ha 3-Cut Z-Cut 3-Cut 2-Cut mt/ha 8M 2.2 2.42 2.50 2.46 2.40 4.5 3.94 3.35 3.25 3.06 9.0 5.14 4.08 4.21 2.77 13.5 5.98 5.22 4.91 4.30 18.0 6.14 5.31 5.10 4.78 22.5 6.05 5.35 5.09 4.57 36-0 1.92. 1.2.2. 2.9.5. 4.5.1. Avg. 4.80 4.62 3.98 3.69 IVDDM 2.2 1.77 1.74 1.82 1.71 4.5 2.90 2.32 2.40 2.19 9.0 3.77 2.80 3.13 2.70 13.5 4.38 3.55 3.70 3.08 18.0 4.50 3.60 3.80 3.43 22.5 4.43‘ 3.62 3.78 3.27 36-0 5.11 _3_-_5.6. 9.7.4. §._24 Avg. 3.73 3.03 3.20 2.80 71 Table 17. Percentage in vitro dry matter digestibility (IVDMD) in the year after seeding of two alfaTTa varieties seeded in the previous spring at six rates and har- vested two or three times in the seeding year (Exp. 1). Cutting Frequency, 1971 Seeding Z-Cuttings 3-Cuttings Variety Rate, kg/ha Number cuttings in 1972 l 2 3 4 1 2 3 4 8 IVDMD I IVDMD Early Seeding, 1971 Saranac 1.1 68.1 64 7 69.2 69.5 67.6 65.2 69.7 69.5 2.2 68.8 65 5 69.3 69.5 67.7 64.9 69.7 69.7 4.5 68.9 65 7 70.1 69.8 67.4 65.1 70.2 69.6 9.0 68.3 64 9 71.1 71.7 67.8 65.1 70.4 70.0 18.0 68.6 65 6 71.0 71.3 68.1 65.5 69.4 70.3 36.0 69.3 64 6 71.3 72.6 68.3 65.4 69.1 70.9 Avg 68.7 65 2 79.4 79.7 67.8 65.2 69.7 79.9 Vernal 1.1 68.8 65 S 70.1 68.7 67.8 64.9 70.3 68.7 2.2 68.8 65.6 70.2 69.6 67.4 65.0 69.0 69.1 4.5 68.3 65.4 70.1 70.1 67.9 64.5 69.2 69.5 9.0 68.8 65.7 69.6 70.8 68.6 65.2 69.8 69.8 18.0 68.8 65.7 70.2 70.4 68.7 65.4 69.0 69.9 36.0 69.3 66.4 71.0 69.9 68.1 65.3 69.3 70.0 Avg. 68.8 65.7 79.2 69.8 6879 65.1 6976 6975 Late Seeding, 1971 Saranac 1.1 68.4 63.7 68.8 69.1 67.5 63.5 68.6 68.8 2.2 68.5 64.1 69.4 69.6 67.4 64.4 68.9 69.1 4.5 69.1 64.1 69.0 69.4 68.2 64.3 68.8 69.5 9.0 68.7 63.9 69.0 69.4 69.0 64.4 68.6 69.5 18.0 68.8 63.6 69.2 70.1 68.6 64.5 69.2 69.4 36.0 69.0 65.0 69.0 70.8 68.8 64.5 69.2 69.4 Avg 68 8 64 1 69.0 69.7 68.3 64 3 68.9 .3 Vernal 1.1 68.8 63 9 70.2 68.8 68.3 64.6 69.5 68.8 2.2 68.5 64.3 68.7 69.1 68.4 64.0 69.5 69.6 4.5 68.5 63.7 68.7 68.9 69.8 64.1 68.6 69.1 9.0 69.2 63.9 70.3 69.0 68.9 64.1 68.5 69.1 18.0 69.2 64.9 69.5 69.4 69.8 65.6 69.6 69.8 36.0 69.3 64.3 70.0 70.4 69.8 65.6 69.3 69.6 Avg. 68.9 63.2 69 5 69.2 6979 64.6 69.1 . Average, Variety and Seeding8pate Average 1.1 68.5 64.4 69.6 69.0 67.8 64.5 69.5 69.0 2.2 68.7 64.9 69.4 69.5 67.7 64.7 69.3 69.4 4.5 68.7 64.7 69.5 69.5 68.1 64.5 69.2 69.4 9.0 68.6 64.6 69.9 70.2 68.6 64.7 69.3 69.6 18.0 68.9 65.0 69.9 70.3 68.8 65.2 69.3 69.9 36.0 69.2 65.0 70.3 70.9 68.8 65.2 69.2 70.0 Avg. 68.8 64.8 69.8 69.9 68.3 6TT8 69.3 6975 Avg. harvests 68.3 68.0 LSD.OS Dates Cuts Varieties RJICS Cut 1 NS NS NS NS Cut 2 NS NS NS NS Cut 3 NS NS NS NS Cut 4 NS NS NS NS 72 Table 18. Percentage in vitro dry matter disappearance (IVDMD) of Saranac ETfaIfa in the year after establishment in summer at six rates and three seeding dates (Exp. 1). Seeding Cuttings Rate 4. 44 kg/ha Cut 1 Cut 2 Cut 3 Cut 4 Avg. Early(July 31) 1.1 67.7 65.8 68.1 69.5 2.2 67.8 65.5 68.5 70.1 4.5 68.9 65.9 68.7 70.2 9.0 69.4 65.2 68.8 69.6 18.0 68.4 65.4 69.1 70.8 36.0 67.3 65.3 69.9 69.1 Avg. 68.7 65.5 68.7 69.9 68.1 Medium (Aug 13) 1.1 68.3 66.9'* 68.3 69.6 2.2 67.9 67.3 70.1 69.7 4.5 68.0 66.8 70.7 70.5 9.0 68.8 67.1 70.2 70.2 18.0 68.6 67.2 70.2 69.6 36.0 68.5 66.9 70.6 70.5 Avg. 68.3 67.9 79.9 79.9 68.8 Late Au 27) 1.1 70.0 68.5 . 68.6 2.2 71.6 67.6 69.2 69.9 4.5 71.0 68.5 69.3 70.0 9.0 71.7 68.4 70.0 70.9 18.0 71.4 67.6 71.6 70.2 36.0 71.4 68.6 71.5 69.2 Avg. 71.7 68.7 79.1 69.8 69.8 Average, Seeding Dates ' 1.1 68.6 67.1 68}6 69.2 2.2 69.1 66.8 69.3 69.9 4.5 69.3 67.0 69.5 70.2 9.0 69.9 66.9 69.5 70.2 18.0 69.4 66.7 70.3 70.2 36.0 69.1 66.9 70.6 69.6 Avg. 69.7 66.9 69.6 69.9 68.9 LSD .05: Dates, NS; Rates, NS. 73 seedings were 2.1% higher in IVDMD than medium- and early—summer seed- ings in the first cutting which indicates that the plants were at a less mature growth stage. The same trend continued in the second cutting in which the late-summer seeding was 1.2% and 2.7% higher than medium- and early-summer seeding, respectively. Comparisons of spring and early- and medium—summer seedings in the next year showed that the IVDMD values were similar in the next year—«68.4 compared to 68.4%, respectively. Late-summer seedings had a slightly higher percentage of 69.8% than early- and medium-summer seedings in the year after seeding, probably because of smaller plants. IV. Phyggphthora Root Rot Studies Experiment 11 Root rot (Phytophthora megasperma Drechs) of alfalfa was identified in Michigan by Dr. A. E. Ellingboe of the Department of Botany and Plant Pathology in roots of alfalfa in September, 1972, in seeding—year studies in Experiment 11, Figure 10. Roots were obtained from the field from three samples each 0.325 m2 in size after the last cutting in the two- or three-cut systems (October 10 and 20, respec- tively) and categorized into four classes, 1 to 4, based on increas- ing severity of infection. The data are presented in Table 19 along with a brief description of the classes presented earlier under Materials and Methods. The highest numbers of healthy plants, 70.3% in class number 1, occurred in early-seeded alfalfa cut only twice during the seeding year. When the alfalfa was seeded late, the healthy roots declined 74 .000000 «a: 00>0>u=4 neue0a .we-ee-00 >00>eea 000 .50-000 0a>0>434 404:0: .0e0uosouou .06000400 500>aen 000 .440000 veneeu0v.x0u:000- 00 .400000 040.00 000 nae-4.000 414:4 . 5 E4 . 2 51445.: 41545. PP. PP” E” 5.44” fir Er 5044 E: 4.4 45.4.. 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When the alfalfa was cut three times instead of twice, the percentage of healthy plants declined to similar levels of 48.1 and 47.8% for early- and late-seeded alfalfa, respectively. The data indicate that injury was more severe when the plants were put under greater stress, i.e., cutting three times instead of twice. Irrigation decreased the percentages of healthy plants, class 1, and strikingly increased the percentage of slightly diseased plants in class 2 and heavily diseased plants in class 3 under all combinations of dates of seeding and cutting frequency. The heavily diseased plants in class 4 increased in percentage under irrigation but not to the extent as in classes 2 and 3. Saranac had lower percentages of healthy plants than Vernal under irrigation but there was little difference between the two varieties when not irrigated. Increasing seeding rates above 4.5 kg/ha significantly decreased the percentage of healthy plants in the various treatments with some exceptions. The combined disease values described in the Materials and Methods section and reported in Figure 11 are a better indication of the incidence of disease than percent in the various classes, Table 20 and Figure 11. The disease values were significantly higher for irrigated than nonirrigated alfalfa substantiating the results in Table 19 which showed a higher percentage of diseased plants under irrigation, a difference significant at the 1% level. Varieties had similar disease values except that irrigated Saranac had a signifi- cantly higher value at the 1% level than Vernal. Increasing the 76 .**«55. .00500 5«*50 .co5pmmwuu0 mo 5o>o5 0500 000 um mo0uo0hm> 0000. .530 .no50000550 mo 5o>o5 0504 may 00 mo0uo0am> 0*050 .co05005555 mo 5o>o5 0500 on» pm 4050 .*«*05. .mmc0uuau mmz .mo0uo0am> .«0000. .mucosumohp :o00000550 502 .40000 "coozpon 000 00.5 55.5 00.5 00.5 50.5 00.5 00.5 00.5 55.5 .m>< 000.5 00.5 00.5 00.5 00.5 40.5 00.5 00.5 55.5 0.00 050.5 55.5 00.5 00.5 00.5 00.5 50.5 00.5 50.5 0.00 000.5 00.5 00.5 00.5 00.5 00.5 00.5 00.0 05.5 0.05 000.5 05.5 50.5 50.5 00.5 00.5 00.5 00.5 05.5 0.05 000.5 05.5 00.5 00.5 00.5 50.5 00.5 50.0 05.5 0.0 000.5 00.5 00.0 00.5 00.5 50.5 05.5 50.5 00.5 0.0 0.50.5 50.5 00.5 00.5 04.5 05.5 00.5 05.5 50.5 0.0 400uo5nw> owwno>< 50.5 50.5 50.5 00.5 50.5 00.5 55.5 55.5 00.5 .0>< 00.5 55.5 00.5 00.5 05.5 00.5 55.5 50.5 50.5 0.00 00.5 55.5 00.5 50.5 50.5 00.5 05.5 05.0 55.5 0.00 00.5 05.5 00.5 00.5 00.5 00.5 05.5 50.5 00.5 0.05 00.5 00.5 50.5 00.5 00.5 00.5 55.5 00.5 05.5 0.05 00.5 05.5 50.5 00.5 00.5 50.5 00.5 00.5 05.5 0.0 00.5 00.5 00.5 50.5 00.5 50.5 00.5 50.5 00.5 0.0 00.5 50.5 00.5 00.5 00.5 05.5 50.5 00.5 00.5 0.0 5mcho> 00.5 05.5 00.5 00.5 00.5 00.5 00.5 50.0 05.5 .0>< 05.5 00.5 00.5 00.5 50.5 50.5 50.0 00.0 00.5 0.00 05.5 00.5 00.5 00.5 00.5 00.5 00.0 05.0 50.5 0.00 55.5 00.5 00.5 00.5 00.5 00.5 00.0 00.0 05.5 0.05 00.5 50.5 00.5 00.5 50.5 00.5 00.5 05.0 05.5 0.05 00.5 05.5 00.5 00.5 50.5 00.5 00.5 05.0 00.5 0.0 00.5 00.5 50.5 00.5 00.5 00.5 00.5 00.5 05.5 0.0 00.5 00.5 00.5 05.5 00.5 05.5 00.5 00.5 00.5 0.0 00:0500 menu 550-5 “no-4 .m>< 550-5 530-4 .m>< 530-5 550-0 «0\00 » ovum 5uo0hm> ommno>< . omwno>< 000000555coz 005000555 0:00000 .555 .mme 5505 :5 55mm 5005 me5uoom 005 :5 0044050 5:00 :0 0000000 mo 005000 0:05:0405005 mpoon «M50050 :0 mos5m> 0000400 myocuxmouxnm .00 05005 77 x .4 Paviomuoan ‘ Figure 10. Phytonhthora root rot symptoms in alfalfa plant showing wilted or stunted yellowed leaves and severe damage in the root. cuttings from two to three likewise showed a highly significant in- crease under both levels of irrigated and nonirrigated conditions although the disease level was greater under irrigation. Plants of the two lower seeding rates were significantly less diseased at the 1% level than at higher seeding rates. Disease values under irrigated or nonirrigated conditions were higher when the alfalfa was out three times instead of twice. 78 .500 .50me 0505 :0 00500 00500 50 030 0:0 0:0 00005 :0>00 00 000000 0000050 000000-0005 0:0 -50500 mo 00:00> 0000000 .50 055000 050x 300 0000 me “NW QMF 0.m.u—. Cum mHVNN gm 0.N_N 0.0.5. m._mw OW OWNN \o/Kwnwuwwxx \0 w llll | .. ...... \ \ m x\\\m\\\|.HHHx\-|x\\ 0 x‘--\ ._ u 80..---- w "3000' 50.0 x 30.0 o owh<0_mm_uZOZ 0000500000 00 _0>0_ 0E00 05 50 050 00.53.0500 00 _0>o_ 0E 00 05 50 0.0000. 5.003000 2.004 QMHQOEE N0 NN VN BOWVA BSVBSIO 79 Both alfalfa varieties seeded at low rates of 2.2 and 4.5 kg/ha and irrigated had lower disease values, with one exception, than when seeded at higher rates. Varieties were equally susceptible over all treatments except that Saranac was more diseased than Vernal under irrigation. The classification according to percentage of diseased plants together with the disease values indicates that Phytophthora root disease of alfalfa is more severe under irrigation which sub- stantiates results of Frosheiser (14). Conditions of stress imposed in this experiment induced greater disease. Stress conditions were three cuttings rather than two and late rather than early seeding. SUMMARY AND CONCLUSIONS The effects of early and late springoseeding on two varieties of alfalfa treated with a herbicide and seeded at seven rates and given two cutting systems were evaluated in seeding—year yields, population density, root development, total nonstructural carbohydrates in roots, in 33332 dry matter disappearance of forage, and incidence of EEXEEf phthora megasperma Drechs root rot in experiments in 1971 and 1972 at East Lansing, Michigan. Yields in the year after seeding were used to compare the yield levels and in_!it£2_dry matter disappearance of spring seedings with summer seedings in the year after seeding. The following conclusions can be drawn from the two experi- ments involving various factors of establishment and management of spring-seeded herbicide-treated alfalfa: 1. Yields of alfalfa in the seeding year were reduced when spring seeding was delayed from the earliest possible date in’Spring until 3 to 4 weeks later. 2. Yields in the seeding year were higher under the 3- cutting system than when the alfalfa was cut twice. Levels of total nonstructural carbohydrates in the fall of the seeding year indicated no differences due to effects of the two cutting systems which was verified by no differences in next year's yield. 3. The highest yield was obtained from early-seeded Saranac alfalfa cut three times during the seeding year. Yields in the 80 81 subsequent year were as high as from other treatments indicating this treatment should be exploited for maximum use of alfalfa harvested in the year of seeding. 4. Saranac yielded more than Vernal in the year of seeding when seeded early but not when seeded late. 5. Yield levels in the year after seeding were similar after early- or latesspring seeding or cutting three times instead of twice indicating that alfalfa was not injured more by increasing cut— ting frequency or delayed seeding in the spring. Irrigation decreased seedingvyear yields when compared to nonirrigation in a year of above- normal rainfall primarily because of a marked disease incidence of Bhytophthora megasperma Drechs, especially in the late-seeded alfalfa cut three times. 6. Alfalfa yields in the seeding year increased up to a seeding rate of 9.0 kg/ha when the seeding was early and weed control satisfactory but the rate of 13.5 kg/ha was necessary fbr maximum yields in the seeding year when weed control was unsatisfactory and the seeding was delayed. 7. Yields in the year after seeding from spring-seeded herbicide-treated alfalfa were similar to the recommended early or medium dates of summer seeding, 8. Plant population in the fall of the first and second year after seeding was significantly higher from early than late seedings. 82 9. Cutting either variety two or three times in the seeding year had no significant effects on the number of plants/m2 in the fall of the cutting or in the second year. 10. The number of plants/m2 at the 9—kg/ha seeding rate which produced the maximum yield was 268 over all treatments of cutting and seeding date in Experiment I and 211 at the optimum rate of 13.5 kg/ha in Experiment II. 11. Higher seeding rates of 18 or 36 kg/ha produced lower survival of seedlings with the late seeding or with Saranac in contrast to late seedings or the Vernal variety. 12. Cutting alfalfa two or three times in the seeding year had no effect on weight per root or root yield in the fall of the first and second year. 13. Weight per root and total root yields were influenced more by population density than seeding time at the end of the seeding year. 14. Root yield was constant for any seeding rate beyond the rate necessary for the maximum yield and paralleled top growth at seed- ing rates beyond maximum yields. 15. Over three—fburths of the roots in the spring of the year after seeding were in the top 30 cm, 14.5% were in the 30- to 60-cm zone, and 6.6% were in the 60- to 90—cm zone. 16. Seeding—year levels of total nonstructural carbohydrates in percent were very similar or showed only a slight decrease in both varieties, in all cutting systems, and seeding dates as rates increased from 1.1 to 36.0 kg/ha. Percentages of TNC in roots of seedlings 83 increased gradually as cutting progressed during the seeding year. 17. Irrigation, variety and seeding rate had no effect on dry matter disappearance of the seeding-year forage of alfalfa. 18. The threeccutting system produced higher in_vitrg_dry matter disappearance values and in_vi££g_dry matter yields than 2- cuttings in the seeding year. 19. Summer seedings and spring seedings produced similar percentages of in_vi£rg dry matter disappearance in the year after seeding except fer late summer seeding which had a higher in_viggg dry matter disappearance in the first and second cut. 20. Irrigation treatment increased incidence of Phytophthora root rot in alfalfa roots when the natural precipitation between April 1 to October 31 was 56 cm, 4.5 cm above normal. 21. Varieties were equally susceptible to Phytophthora root rot except that Saranac under irrigation showed somewhat greater sus- ceptibility. 22. Alfalfa seeded at lower seeding rates of 2.2 and 4.5 kg/ha was significantly less diseased than the higher seeding rates when irrigated. 23. Maximum Phytophthora root rot was induced by a combina- tion of stress factors including high moisture levels in the soil, frequent cutting, high seed rates resulting in smaller plants and a susceptible variety. 84 Agronomicggpplication Cutting early-seeded, herbicide-treated alfalfa three times in the seeding year maximized yields when seed rates were 9.0 kg/ha with satisfactory weed control and 13.5 kg/ha when weed control was not satisfactory. Maximum yields produced under this intensive sys- tem of establishment and management produced higher yields of digestible feed than when cut less frequently or seeded later without impairing the survival and productivity of the alfalfa in the following year. B I BL IOGRAPHY 10. 11. 12. BIBLIOGRAPHY Ahlgren, H. L. 1948. Corn Belt and Lake States. U.S.D.A. Yearbook of Agriculture. Washington, D.C., p. 391-454, Allison, D. W., M. B. Tesar, and J. W. Thomas. 1969. Influence of cutting frequency, species and nitrogen fertilization on forage nutritional value. Crop Sci. 9:634037. Anderson, R. H. 1969. Alfalfa establishment studies. North Central Quarterly, No. 4:2. Barnes, R. F., and C. H. Gordon. 1972. Feeding value and on- farm feeding. In C. H. Hansen (ed.) Alfalfa Science and Technology, ASA, monograph No. 15, pp. 601-630. Amer. Soc. Agron., Madison, Wisconsin. Bolton, J. E. 1962. Alfalfa botany, cultivation and utiliza- tion. Ch. 18, pp. 391-435. Interscience Publ. Inc., New York. Brown, C. S., and R. F. Stafford. 1970. Get top yields from alfalfa seedlings. Better Crops with Plant Food. 54(1): 16-18. Bula, R. J., and M. A. Massengale. 1972. Environmental physio- logy, Ch. 8, In C. H. Hansen (ed.), Alfalfa Science and Technology, pp. 167-184. Amer. Soc. Agron, Madison, Wis- consin. Bushong, J. W., and J. W. Gerdemann, 1959. Root rot of alfalfa caused by Phytophthora cryptogea in Illinois. Plant Disease Rept. 73:1178-1183. Chi, C. C. 1966. Phytophthora root rot of alfalfa in Canada. Plant Disease Reptr. 50:451-453. Clements, F. E., J. E. Weaver, and H. Hanson. 1929. Plant competition. Carnegie Inst. of Washington, Pub. 398. Cowett, E. R. and M. A. Sprague. 1962. Factors affecting tillering in alfalfa. Agron. J. 54:294—297. Ervin, D. C. 1954. Root rot of alfalfa caused by Phytophthora cryptogea. Phytopathology, 44:700-704. 85 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 86 Frosheiser, F. I. 1967. Phytophthora root rot of alfalfa in Minnesota. Plant Disease Reptr. 51:679-681. Frosheiser, F. I. 1969. Phytophthora root rot of alfalfa in the upper midwest. Plant Disease Reptr. 8:595-97. Fuess, F. W. and M. B.. Tesar. 1968. Photosynthetic efficiency, yields and leaf loss in alfalfa. Crop Sci. 8:195-63. Graber, L. F., N. T. Nelson, W. A. Luekel, and W. B. Albert. 1927. Organic fbod reserves in relation to the growth of alfalfa and other perennial herbaceous plants. Wisconsin Agr. Exp. Sta. Res. Bull. 80, 128 p. Graffis, D. W. 1969. Going it alone. Spring establishment of alfalfa without companion crop. Better Crops with Plant Food, 4:8-9. Graffis, D. W. 1969. Alfalfa seeding rate studies. NCR-Sl, Committee, Forage Management and Physiology. Graffis, D. F. 1970. Alfalfa-grass mixture seeding rates. NCR-Sl Committee, Forage Management and Physiology. Grandfield, C. 0. 1935. The trend of organic food reserves in al- falfa roots as affected by cutting practices. J. Agr. Res. 50:697-709. Jackobs, J. A. and D. A. Miller. 1970. Varying seeding rates of alfalfa blends. Agron. Abstr., ASA, p. 80. Johnson, H. W., and F. L. Morgan. 1965. Phytophthora root and crown rot of alfalfa in the Yazoo-Mississippi Delat. Plant Disease Reptr. 49:753-755. Lamba, P. S., H. L. Ahlgren and R. J. Muckenhirn. 1949. Root growth of alfalfa, medium red cloves, bromegrass and timothy under various soil conditions. Agron. J. 10:451- 458. Moline, W. J. and L. R. Robinson. 1971. 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