SOME FAC‘E‘ORS AFFECTING SEED PRODUCTiON <35: RUSSiAN WILDRYE {Elymus juncous Fish} ‘Jhwsis éar rm Degree of Ph. D. MICHmAN STATE UNIVERSWY Lavarna M. Fewer“ 1962 TEE-4H1? This is to certify that the thesis entitled SOME FACTORS AFFECTING SEED PRODUCTION OF RUSSIAN WILDRYE (Elymus junceus Fisch.) presented by Laverne M. Powell has been accepted towards fulfillment of the requirements for Ph-Do degree in Farm Crops /' ‘ f I ’1 _ - . ,_ _ _ / ’l l I ( -" r I ,’ .‘ I _I:_ . ( '1 K Major professor 0-169 LIBRARY Michigan State University plant: primo: that ' initi July low t flowe Primc one l Plan free fail Same Cati grow Plat ABSTRACT SOME FACTORS AFFECTING SEED PRODUCTION OF RUSSIAN WILDRYE (Elymus junceus Fisch.) By Laverne M. Powell Examination of over-wintering tillers on Russian wildrye plants dug from frozen soil in early Spring revealed that floral primordia were present on those tillers and only those tillers that had formed 7 leaves. Further examination indicated that the initiation of new floral primordia occurred on such tillers during July at which time seed was maturing in the spikes. No combination of exposure of seeds or young seedlings to low temperature; length of day, or nutritional differences induced flowering. Even though an abundance of tillers possessing primordial floral parts were found on plants that had grown for one or more seasons, development of spikes occurred only on those plants that had been exposed to a considerable amount of sub- freezing weather. Plants that had received scanty nitrogen fertilization failed to produce Spikes under conditions where portions of the same clone headed well with high nitrogen fertilization. Appli- cation of nitrogen at such a time as to avoid excessive fall growth appeared helpful, with that in late September being more beneficial to spike deve10pment than late August. Mechanical disturbance in the spring of sturdy field-grown plants was found, in limited experiments, to lead to greatly decr were froz prod Fiel fact diff flor vigo: prob prim< founc be an wyomi the a nutri at th distu at th benef Laverne M. Powell decreased seed production when compared to adjacent plants that were left undisturbed. However, when plants were dug from the frozen soil and subdivided into separate pots, the segments produced spikes as freely as did similar undisturbed plants. Field competition for nutrients and moisture appears to be a factor in preventing the development of spikes from previously differentiated floral primordia. Russian wildrye is an erratic seed producer. Nevertheless, floral primordia were found to form on virtually all of the more vigorous tillers after seed was formed on fruiting tillers. The problem appears to be that of inducing these reproductive primordia to complete deve10pment. Although a considerable period of freezing temperature was found necessary for continued develOpment, this requirement should be met more than adequately by winter exposure in Michigan or wyoming. From the series of experiments conducted, it appears that the answer to the problem may be found in adjusting nitrogen nutrition to give vigorous growth and abundant tillering while at the same time avoiding excessive crowding or mechanical disturbance in the Spring. A condition of high nitrogen nutrition at the time the grass went into the winter appeared to be highly beneficial. SOME FACTORS AFFECTING SEED PRODUCTION OF RUSSIAN WILDRYE (Elymus junceus Fisch.) By Laverne M. Powell A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Farm Crops 1962 .. r“. Acknowledgement The author expresses his appreciation to Dr. S. T. Dexter for his counsel, encouragement, and helpful comments during this study. Some plant material was furnished by Dr. 0. J. Hunt, Agricultural Research Service, U. S. Department of Agriculture, Laramie, Wyoming. Mr. K. C. Feltner supplied plants and tiller samples from this source as well as seed from.a Wyoming grower. Dr. F. C. Elliott of Michigan State University also furnished seed for this study. Further acknowledgement is given the late Dr. G. P. Stein- bauer for his suggestions on the physiology and growth of plants which aided the author in this study. The author wishes to thank Dr. C. M. Harrison, Dr. E. H. Everson, and Dr. I. W. Knobloch for their critical review of the thesis. ii TABLE OF CONTENTS Page INTRODUCTION 1 REVIEW OF LITERATURE 4 Rows 5 Nitrogen 6 Cold Induction 7 Photoperiod 8 Ripeness to Flower 10 Tillering ll Anatomy of Flowering 13 MATERIALS AND METHODS 15 Nutrient-Photoperiod 15 PhotOperiod 18 Seed Conditioning 19 Seedling Cold Treatments 23 Natural Cold Treatments 25 Head Removal 26 Field Nitrogen and Plant Disturbance 29 Anatomical Studies 31 RESULTS AND DISCUSSION 33 Nitrogen-Photoperiod 33 Photoperiod 35 Seed Conditioning 36 Seedling Cold Treatments and Natural Cold Treatments 39 Head Removal Test 41 Field Nitrogen and Plant Disturbance 42 Anatomical Studies 50 SUMMARY 56 LITERATURE CITED 58 iii List of Tables Page Table l. Treatments given each plant in the nutrient- photoperiod test. 18 Table 2. Head removal data and photoperiod under which the plants were grown prior to and during test. 29 Table 3. Number of seedlings emerged during 13 days after receiving cold treatments. 36 Table 4. Number of seedlings emerged during 7 days after receiving cold treatments. 38 Table 5. Number and percent reduction of heads produced in relation to date of nitrogen application and disturbance (division) on April 14, 1961. 44 Table 6. Number and percent reduction of heads produced in relation to rate of nitrogen application and disturbance (division) on April 14, 1961. 44 Table 7. Number of heads produced by 3 undisturbed plants per plot in relation to rate and date of nitrogen application. 45 Table 8. Number of heads produced by 3 divided plants in relation to rate and date of nitrogen application. 45 Table 9. Production of heads in relation to date and rate of nitrogen application expressed in percent of heads produced by unfertilized plants. 47 iv Figure Figure Figure Figure Figure Figure Figure Figure List of Figures Page 1. Russian wildrye plant. Upper view shows plant as taken from the field. Lower view Shows plant divided into segments for potting. 16 2. Tiller group of Russian wildrye showing the characteristic 4 tiller group. The culm second from the right is the main culm. 28 3. Russian wildrye plants showing typical bunch growth with abundance of basal leaves. Upper photo, taken October 18, 1960, shows growth of seedlings first year. Lower photo, taken May 20, 1961, shows older plants spaced 24 x 24 inches. 34 4. Seedlings in flat FC-7 upon removal from the cold chamber. 40 5. Result of root disturbance. A small section of tillers was removed from each of the 3 plants on the left on April 14, 1961. The plants on the right were undisturbed. 43 6. Photo taken October 10, 1960, showing the 10 plants in the test FN-II in the foreground. They were grown in soil from March 9 to October 8 in 8 inch pots without additional fertilizer. 49 7. Typical vegetative growing points of Russian wildrye. Upper left hand drawing shows a vege- tative growing point almost enclosed by a devel- oping leaf, enlarged approximately 300 times. Lower right hand drawing shows a vegetative growing point, enlarged approximately 600 times. 51 8. Growing points of Russian wildrye changing to the reproductive stage. The start of double ridges is shown in the right hand drawing. Both drawings are enlarged approximately 100 times. 52 Page Figure 9. A reproductive growing point of Russian wildrye. The double ridges are clearly evident. The drawing is enlarged approximately 50 times. 53 Figure 10. A reproductive growing point of Russian wildrye at the beginning of Spikelet formation, enlarged approximately 40 times. 54 vi Introduction Forage production for livestock grazing is an important factor in the economy of the Northern Great Plains area. An ideal forage should start growing early in the Spring and continue growth throughout the summer into the late fall. It also should be palatable and highly nutritous, long-lived, and easy to establish. One of the major factors in establishing any crop is the availability of seed at a nominal cost; therefore, seed production of any desirable crop is of great importance in the eventual economic utilization of that crop. Russian wildrye (Elymus junceus, Fisch.)1 (ll, 13, 28, 33, 34) is native to the dry saline soils of the steppes from Iran northward to the lower Volga and lower Don river regions of the U.S.S.R., eastward into western Siberia and across Asia to Outer Mongolia. According to Rogler (34), one of the early introduction of Russian wildrye was F.P.I. 75737 which was obtained by the Division of Plant Exploration and Introduction from the Western Siberian Experiment Station at Omsk, U.S.S.R., in 1927. Later 1Scientific nomenclature is according to Index Kewensis. introductions were made in 1934 and 1935 by the Westover-Enlow Expedition. It has been grown at the Northern Great Plains Field Station at Mandan, North Dakota, since 1927. Rogler (33, 34) describes this grass as a long-lived perennial bunchgrass producing erect, naked stems. It has coarse fibrous roots which grow to a depth of 8 to 10 feet; however, 75 percent of the roots are in the surface 6 inches of the soil. The roots have a wide horizontal spread, taking moisture from a distance of 4 or 5 feet from the crown. This species of grass has an abundance of dense, basal leaves which are 6 to 18 inches long, about 1/4 inch wide. The leaves are moderately soft and lax. Hafenrichter (9) states that Russian wildrye is entirely winterhardy and drouth resistant once it has been established and that no other exotic grass adapted to the Northern Great Plains is as high in digestibility and nutritive value throughout the growing season. Although Russian wildrye makes its maximum growth under cool temperatures, it makes more growth during the summer than do most cool season grasses. It matures seed earlier than most grasses. This grass remains palatable after the seed heads have matured and continues to produce an abundance of basal leaves and tillers. It makes greater and more rapid regrowth than most grasses of the Great Plains after the top growth has been removed either by mowing or grazing by livestock. The major reason for the lack of widesPread use of this species of grass is the high cost of the seed and the absence of a reliable source of seed. This is caused by the erratic seeding habit of Russian wildrye (6, 9, 33, 39). The erratic habit of seed production does not seem to be one of a cyclic nature as a given field of Russian wildrye may produce seed two or three years in succession and then not produce an appreciable amount of seed the following year or years. Or, on the other hand, it may not produce seed for one or more years and then, for some unknown reason, it may produce a large seed crop. Even in a given area, all seed fields do not act alike in producing seed. The conditions necessary for successful seed production of Russian wildrye are not known. Therefore, information which would delineate the factors affecting the successful production of seed of this grass would be a definite contribution to seed producers and breeders of Russian wildrye. Review of Literature A search of the literature reveals that little has been published on seed production of Russian wildrye. None of the various treatments reported has given consistent production of seed. It is not known whether the major problem in the production of Russian wildrye seed is floral induction or floral development after induction has occurred. Therefore, this review covers the known information which concerns the factors affecting floral induction and floral deve10pment. Many workers have noted that floral induction, initiation and development are three distinct and separate stages of plant growth and that each stage may require a different environment, depending upon the species concerned. Lindsey and Peterson (18) stress that there is a clear distinction between the requirements for induction and for floral development. According to Whyte (45) the stages of develOpment occur in strict sequence and each one must be completed before the next stage starts. Breeding work has resulted in the release of the variety Vinall Russian wildrye. Schaaf and Rogler (36) reported the variety to be a more reliable seed producer than common Russian wildrye. Even though this new variety does show some improvement in seed production, the production of seed is still erratic. 4 Rows It is known that row Spacing is important in the production of seed of many crops. Some research has been done in an attempt to determine the effect of row Spacing upon seed production of Russian wildrye. McWilliams (20), working with Russian wildrye at Mandan, North Dakota, found that best seed production was obtained when the grass was grown in rows that were spaced 18 inches or more apart. Stelfox, Heinrichs and Knowles (38) state that row Spacing is the most important factor in seed production at Saskatchewan and Alberta, Canada. According to them, the optimum row width is from 2 to 4 feet. However, seed production of Russian wildrye at any row width was not consistent. Stitt (39) states that the row spacing for seed production should be 18 to 24 inches at Moccasin and Harve, Montana. He also found that regardless of row width, the seed production was erratic. This would indicate that although row width is important, there are other factors which greatly influence seed production of Russian wildrye. The reason why the minimum Spacing between rows, as reported by McWilliams (20) for North Dakota or Stitt (39) for Montana or Stelfox, Heinrichs and Knowles (38) for Canada, should vary for these areas is not apparent. The density of the popula- tion of plants may have been the reason that the recommended row widthlvaried, as greater Spacing between plants within the row might allow closer Spacing of the rows. Nitrogen Considerable research has been done on the effect of nitrogen upon seed production of various species of plants. Murneek (24) states that a relatively high nitrogen content has been noted to be associated with floral initiation. He found (23) that parts of tissues on the same plants or portions thereof may range from juvenile to senescent stages and through all stages of reproductive develOpment. He further states that chemical analysis of whole plants or large portions of them are difficult or impossi- ble to interpret and of little value. According to him, nitrogen is one of the most critical elements in the initiation of sexual reproduction and it is often a limiting factor in the production of fruits and seeds. In working with tomatoes, he found that ample nitrogen gave more fruits. Langer and Lambert (15), investigating the head-bearing capacity of tillers arising at different times in forage grasses grown for seed in England, found that the earliest tillers con- tributed the most to the number of heads at harvest. Application of nitrogen caused an increase in the number of tillers. They found that when meadow fiscue was grown under low nitrogen con- ditions, 68 percent of the heads came from early tillers and when grown under high nitrogen conditions, 75 percent of the heads came from early tillers. Neidle (26) working with Xanthium pennsylvanicum plants found that plants with a high supply of nitrogen produced more burs regardless of the photOperiod. Working with Kentucky bluegrass, Peterson and Loomis (27) found that plants given extra nitrogen produced about 5 times as many flowers as those which did not receive any extra nitrogen. Watkins (43) found when nitrogen was applied to smooth bromegrass, the number of fertile shoots was increased as well as the total number of shoots and rate of leaf production. Heinrichs and Lawrence (13) found that extra nitrogen was needed for seed production of Russian wildrye. They also state that nitrogen applied in August is more effective than when the nitrogen is applied in the spring. Rogler (33) states that nitrogen should be applied in the fall. In years of adequate moisture, seed production of Russian wildrye was increased the year following the application of nitrogen, according to Stelfox, Heinrichs and Knowles (38). Stitt (39) states that response to nitrogen, for the production of Russian wildrye seed, is limited to the year follow- ing the application of the nitrogen. As in the case of row width, the application of nitrogen did not consistently give good seed production in any of the areas reported. This would indicate that while adequate nitrogen is important, other factors are also important in seed production. Cold Induction According to Rogler (33, 34) and Schaaf (35), Russian wildrye does not produce seed the season in which it is planted. The fact that no seed is produced the year of seeding, even though it is seeded early in the spring, suggests that a period of cold may be needed for the successful develOpment of seed heads or that sufficient development of the planugmay not occur early enough in the season. Periods of cold have been found to be necessary for floral development of several species of plants. Went (44) states that northern trees in general need a minimal number of hours of chilling. The hours of chilling need not be consecutive as the effect is accumulative. Northern varieties generally need longer periods of chilling than southern varieties. Langer (17) has found that timothy has no cold requirement. According to McKinney and Sando (19), the reproduction of wheat is not dependent upon a critical temperature but reproduction is greatly affected by temperature. Purvis (29, 30) has found that lack of vernalization greatly delays the flowering of winter rye. She also found that vernalization is reversible by high tempera- ture. Also, the rate of growth of the Spike is increased by vernalization (33). Photoperiod Photoperiod is known to have a considerable effect upon floral initiation and floral development of many plants. The effect of photoperiod upon Russian wildrye seed production has not been established. Benedict (1) found that blue grama (Bouteloua gracilis) is indeterminate for photOperiod. It flowered under day lengths of from 8 to 20 hours if the temperature was held at 75°F. but would not flower at any day length at temperature of 65°F. The role of environmental interactions in flowering is emphasized by Doorenbos and Wellensiek (5). They state that the complexity of the flowering process is becoming more evident. This is in agreement with Templeton, Mott and Bula (41) who found that flowering of a given plant may be induced by different combinations of environmental factors. McKinney and Sando (19) state that reproduction of wheat is not dependent upon photOperiod alone but that photoperiod and temperature have a great effect upon reproduction. Peterson and Loomis (27) working with Kentucky bluegrass found that floral induction occurred in the fall under short days and cool temperatures. No flowers were formed the following season if the fall photoperiod was long or warm. They found that follow- ing induction, long days gave the Optimum floral development. Winter rye has two Optimal photoperiods according to Purvis (29). She states that short photoperiods for 6 weeks followed by long photoperiods are best for rye; however, there is no critical photoperiod for differentiation in winter rye. Working with selected genotypes of orchardgrass, Chilcote and Bula (4) found that one strain normally required a 14 hour photoperiod; however, when held at 22°C. for 8 hours of photo- period and at 22°C. for 16 hours of dark, the plants were induced in 16 consecutive days. After induction, long days of 20 hours at a temperature of 15°C. were most favorable for floral development of the strains tested. 10 Skok, Scully and Norbert (37) state that photoperiod has no effect on floral initiation in Tartary buckwheat but that photo- period markedly influences the floral deve10pment and fruiting. Hanson and Sprague (10) working with orchardgrass, meadow fescue, bromegrass, reed canarygrass and timothy in the greenhouse found that the best seed production was secured when the plants were kept at 55°F. and given short day photoperiodiuntil induced and then given long day photOperiods at 75°F. until seed heads were produced. Wanser (42) and McKinney and Sando (19) found that wheat needs a different photoperiod for each of the three stages: induction, joint elongation, and heading. Ripeness to Flower Von Denffer, as reported by Whyte (46), established a direct relationship between leaf numbers and time of flower formation. Whyte terms this stage of development ripe-to-flower. Bula (3) states that the relationship between light intensity and length of photoperiod appears to be one of providing a maximal growth rate to ripe-to-flower. He found that floral stems are initiated when the ripe-to-flower stage is reached and the plant is under a favorable flowering environment. He suggests that a large segment of the plant population in Dollard red clover does not reach this ripe-to-flower stage in time to produce flowers the first year. In accordance with this, Schaaf (35) working with Russian wildrye, suggested that the physiological age of the individual 11 tiller when growth ceases in the fall somehow determines whether it will produce a culm the next year. In winter rye germinated at 1°C. for 4 weeks, Purvis (30) found that flowering did not take place until 10 leaves had been formed. She also found that the minimal number of leaves on summer rye was 7 before flowering could occur. Langer (17), working with timothy in England, found that the tillers produced in November had an average of 13.8 leaves at time of flowering; the tillers produced in May had an average of 7.0 leaves; and the least number of leaves found on a tiller was 6 on the tillers produced in May. This would suggest that a physiological stage must be reached and that the minimal number of leaves is affected by the environment. This is in accordance with work done by Purvis (30, 31) on winter rye. She found that the number of leaves at flowering time was affected by the environment; but, regardless of environment, the minimal number of leaves could not be reduced below a given number. Tillering Templeton, Mott and Bula (40), investigating the effects of temperature and light on growth and flowering of tall fescue, found that tillering was influenced by several interactions: photoperiod X temperature, photoperiod X age, photoperiod X temperature X plant source, temperature X age of plant, and temperature X duration of treatment. They concluded that tillering is a complex process and that apparently the morphological 12 development of young grass plants reflects, to a great degree, a biological integration of their external and internal environments. Langer (17), investigating the life history of individual tillers of timothy in England, found that tillers generally started to deve10p from the bottom axil, but under some environments the higher axils developed tillers first. According to Mitchell (21, 22), lateral bud development of ryegrass is inhibited by shading, short photoperiod, high tempera- ture and partial defoliation. When investigating the heading capacity of tillers arising at different times in herbage grasses grown for seed in England, Langer and Lambert (15) found that the tillers that appeared in March and April made a negligible contribution to the heads produced. Research by Schaaf (35) on the effect of planting date on seed production in Russian wildrye at Mandan, North Dakota, revealed that while no seed was produced the year of seeding, the largest seed yields the following year were obtained from the earliest plantings. This would indicate that early, well-develOped tillers are the ones contributing most to seed production. Lamp (14) found that in bromegrass, the center of the clump was less favorable for growth and reproduction than the periphery of the clump. He also found that floral primordia occurred first on the autumn tillers and next on the spring tillers and both fertile and sterile culms were produced. l3 Anatomy of Flowering Langer (16) found that elongation of the culm in timothy plants starts before the growing point changes from the vegetative stage to the reproductive stage. These conditions have not been noted in Russian wildrye. Bonnett (2) investigated the development of the barley Spike which has the same type of development, in general, as other grasses producing a spike. He found that stem deve10pment con- sisted of two Stages. In the first stage, the internodes remain short and the growing point is hemispherical in shape. During the latter part of this stage, the primordium begins to elongate. At the start of the second stage of stem development, the internodes begin to elongate and the growing point, which has elongated, develOpS double ridges on it. Purvis (29) states that the appearance of double ridges can be taken to indicate that floral initiation has begun. This is in accordance with work done by Esau (7) on wheat. According to Bonnett (2), the upper ridge of the double ridges deve10ps into the Spikelet and the lower ridge probably develops into the internode of the rachis. The lower ridge of the double ridge, according to Esau (7) develOps into a subtending leaf primordium in wheat. She states that this is typical of grasses having a spike-type head. Purvis and Gregory (31) state that in rye the lower ridge develops into the subtending bract of the Spikelet. They further state that the development of either of the two ridges may be inhibited by adverse environmental conditions. 14 Purvis and Gregory (31) found that in winter rye, the primordia between the eighth and twenty-fifth are indeterminate and will produce either leaves or Spikelets as related to the structure of the initials which are double, Spikelet and subtending bract, either of which may be inhibited by an unfavorable environment. Plants with a terminal flowering habit can be readily changed from a flowering to a vegetative state by being placed under an environment which inhibits flowering, according to Roberts and Struckmeyer (32). Materials and Methods Since the factor or factors which cause the inconsistent production of seed by Russian wildrye have not been reported, several tests of various nature were conducted in an attempt to delineate the factors affecting seed production of Russian wildrye. Nutrient-Photoperiod The first test, NP-I, was conducted to determine the effect of photOperiod and/or fertilizer, when applied from the start of regrowth in the Spring until heading had occurred, upon the heading of Russian wildrye. The plants were established from seed planted in March, 1958, in 2 inch plant bands at Laramie, Wyoming. The plants were transplanted in the Spring of 1958 into a field which had been fertilized at the rate of 200 pounds of nitrogen per acre and received no additional fertilizer. Test plants were dug from this field in March 1960, while the ground was still frozen, wrapped in burlap, packed in snow, and sent to East Lansing, Michigan, by air freight. They were kept frozen until March 8, 1960, when they were thawed out, divided, and planted in 8 inch pots, Figure l. 15 Figure 1. Russian wildrye plant. Upper view shows plant as taken from the field. Lower view shows plant divided into segments for potting. l7 Twenty-one segments were potted in washed sand after washing any adhering soil from the roots and crowns. The remaining 42 segments were potted in soil. Eighteen of the plants potted in sand and 12 potted in soil were used in this test, Table l. One-half of the plants from each group were grown under an 8 hour photoperiod and the others were given supplemental light from 8:00 p.m. until 4:00 a.m. Each plant was given 250 ml. of nutrient solution A, B, or C 3 times each week from time of potting until the plants headed. One-half molar stock solutions were made from the following chemicals: KH2P04, CaClZ, Ca(N03)204H20 and MgSOa-7HZO. Nutrient solution A (minus nitrogen) was made by adding 9 m1. of 1/2M.KH2PO4 stock, 18 ml. of l/ZM CaClz stock and 9 ml. of l/2M MgSO4-7H20 stock to enough water to make 1 liter of solution. Nutrient Solution B (complete) was made by adding 9 ml. of l/ZM KH PO4 stock, 18 ml. of l/2M Ca(NO 2 ~4H20 stock and 3’2 9 ml. of l/2M MgSO4-7H20 stock to enough water to make 1 liter of solution. Nutrient solution C (extra nitrogen) was made by adding 9 m1. of l/2M.KH2PO4 stock, 36 m1. of Ca(NO3)2°4H20 stock and 9 ml. of 1/2M.MgSO4-7H20 stock to enough water to make 1 liter of solution. The plants were arranged in a randomized 3-factor design with photoperiod being the main plots, fertilizer as the subplots and potting medium as the sub-subplots. 18 Table l. Treatments given each plant in the nutrient-photoperiod test. Nutrient Nutrient Pot solution Potting Photo- Pot solution Potting Photo- No. given1 medium period2 No. given1 medium period2 l C Sand SD 16 -N Sand LD 2 +N Sand SD 17 C Sand LD 3 -N Sand SD 18 +N .Sand LD 4 +N Sand SD 22 +N 8011 SD 5 C Sand LD 23 C Soil SD 6 +N Sand LD 24 +N Soil SD 7 -N Sand LD 26 C Soil LD 8 +N Sand LD 27 +N Soil LD 9 -N Sand LD 40 C Soil SD 10 -N Sand SD 41 +N Soil SD 11 C Sand SD 42 C Soil SD 12 -N Sand SD 43 +N Soil LD 13 C Sand SD 44 C Soil LD 14 +N Sand SD 45 +N Soil LD 15 C Sand LD 56 C Soil LD 1 C = Solution B (complete) +N - Solution C (extra nitrogen) -N 8 Solution A (minus nitrogen) 2SD 8 Eight hour photoperiod (short day) LD I Normal day length plus lights (long day) Photoperiod For test P-II, additional plants from the Laramie, Wyoming, nursery were received at East Lansing, Michigan, on January 19, 1961. The plants were thawed out, divided, and planted in 5 and 8 inch pots 19 on January 20, 1961. One-half of the plants were grown under natural day length and the others were given supplemental light from 5:00 p.m. until midnight. The plants were sampled when planted on January 20 to determine the stage of development of the primordia. In test P-III plants were brought from the field on December 8, 1961, to the greenhouse in Laramie, Wyoming. Seven plants were grown under natural day length and 10 plants were grown under long day conditions with additional light from 5:00 p.m. until 11:00 p.m. Seed Conditioning Three trials were made to determine whether cold treatment of Russian wildrye seeds would cause the plants to produce seed the year in which they were planted. In the first trial, SC-I, the seeds were treated as follows: SC-l. The seeds were soaked in water for 30 minutes, then the excess water was drained off. The seeds were held at room temperature for 72 hours on moist blotter paper to start germina- tion, after which they were held at -5°C. for 24 hours and then planted. SC-2. Water was added to the seeds in this treatment at the rate of 1 gram of water for each gram of seed. These seeds were then held at room temperature for 72 hours and 2°C. for 24 hours. SC-3. One gram of water for each gram of seed was added to the seed. The seeds were then held at room temperature for 20 24 hours. They were then held at 2°C. in an Open vial for 10 days at which time the seeds were Spread out upon a wet blotter in a petri dish and continued to be held at 2°C. for an additional 16 days. 86-4. The seeds in this treatment were treated the same as in SC-3 above except upon transfer from the vial to the petri dish, they were placed on a dry blotter and held at 2°C. for the last 16 days under high humidity conditions. SC-5. These seeds were not treated and were used as a check. Twenty seeds from each treatment were planted in potting soil in flats on March 25, 1960. The number of seedlings emerged were counted daily from the third through the thirteenth day after planting. All of the emerged seedlings were transplanted into peat pots April 8, 1960. The plants were transplanted, without removal from the pots, into the field on June 16, 1960. In the second trial on cold treatment of seeds, 86-11, all of the seeds were submerged in water for 2 minutes and then placed on a screen to drain for 8 hours. They were then given the following treatments: 80-6. The seeds were held at room temperature in a vial at high humidity for 72 hours. The vial of seed was then held at 2°C. for 8 days after which the seeds were Spread out on a wet blotter in a petri dish and held at 2°C. for an additional 20 days. The seeds were then removed from the petri dish and dried at room temperature for 8 days. 21 SC-7. The seeds were held at room temperature for 24 hours after soaking. They were then transferred to a petri dish and held at 2°C. for 30 days and then held at room temperature for 8 days. 86-8. The seeds were held at room temperature in a petri dish for 24 hours after soaking. They were then held at 2°C. for 38 days under high humidity. SC-9. The seeds were held at room temperature in a petri dish for 72 hours, then held at 2°C. under high humidity for 36 days. SC-lO. This seed was used as a check and given no treat- ment prior to planting. Twenty seeds from each of the treatments were planted April 4, 1960, in a flat containing potting soil. The emerging seedlings were counted daily from the second through the seventh day after planting. No seedlings emerged after the seventh day so the seedlings were tranSplanted into individual peat pots and transplanted into the field June 16, 1960. In the third trial, SC-III, the cold treatment was given to dry seeds as well as seeds which had been soaked. The seeds which were given the cold treatment while wet were soaked in water for 6 hours and then drained. The seeds were then given additional treatments as follows: SC-ll. Soaked seeds were placed in a petri dish and stored for 12 days at -5°C. No additional moisture was given to the seeds during this period. At the end of 12 days the seeds were allowed to dry out at room temperature for 11 days. 22 80-12. Soaked seeds were placed in a petri dish and stored for 12 days at -5°C. under high humidity to prevent the seeds from drying out. At the end of the cold period, the seed was allowed to dry at room temperature for 11 days. SC-l3. This treatment consisted of storing dry seeds at -5°C. for 12 days and then at room temperature for 11 days. SC-l4. Soaked seeds were placed in a petri dish and stored for 12 days at 2°C. No additional moisture was added during this period. At the end of 12 days of cold, the seeds were held at room temperature for 11 days. SC-15. Soaked seeds were placed in a petri dish and Stored at 2°C. for 12 days under high humidity. They were then allowed to dry at room temperature for 11 days. SC-l6. This treatment consisted of Storing dry seeds at 2°C. for 12 days and then at room temperature for 11 days. SC-17. Soaked seeds were placed in a petri dish and stored at -5°C. for 23 days. The seeds were then held at room temperature for 4 hours prior to planting. SC-l8. Soaked seeds were placed in a petri dish and stored for 23 days at -5°C. under high humidity. The seeds were held at room temperature for 4 hours before planting. SC-19. Dry seeds were stored at -5°C. for 23 days and then at room.temperature for 4 hours. SC-20. Soaked seeds were placed in a petri dish and stored at 2°C. for 23 days. No additional moisture was added during this period. The seed was then held at room temperature for 4 hours. 23 SC-21. Soaked seeds were placed in a petri dish and held at 2°C. for 23 days under high humidity. The seeds were then held at room temperature for 4 hours. SC-22. Dry seeds were held at 2°C. for 23 days and then 4 hours at room temperature. 30-23 and SC-24 were checks in which the seed received no treatment prior to planting. SC-23 consisted of seed grown in Michigan the previous year. SC-24 consisted of seed grown in Wyoming the previous year. Twenty seeds from each treatment were planted in flats April 16, 1960. The number of seedlings that had emerged were recorded daily from the third through the seventh day after planting, after which no more seedlings emerged. The seedlings were tranSplanted into individual peat pots June 16, 1960, and then transplanted to the field June 20, 1960, without removing the plants from the peat pots. Seedling Cold Treatments A test, FC-I, was conducted to determine whether Russian wildrye seedlings could be vernalized without going through winter cold. The seed was planted February 10, 1960, in flats. After the seedlings had emerged, each seedling was transplanted into a 2 inch peat pot. Twenty potted plants were put into each flat for cold treatment. The plants in flat FC-3 were used as checks and were not given a cold treatment. 24 Flats FC-1 and FC-2 were put into a cold chamber without light. The plants were 8 weeks old when the cold treatment was begun on April 6, 1960. The temperature of the chamber was held between 34°F. and 36°F. during cold treatment. Flats FC-4 and FC-5 were put into a cold chamber which had fluorescent lights giving the plants a 10 hour light period. The temperature of the chamber was held between 32°F. and 34°F. during the light period while the temperature during the dark period was between 30°F. and 32°F. for the duration of the test. Flats FC-2 and FC-5 were removed from the cold chambers on April 23, 1960, after 17 days. They were then placed in a warm greenhouse under long photoperiod which consisted of natural daylight supplemented by lights from 8:00 p.m. until 4:00 a.m. Flats FC-1 and FC-4 were removed from the cold chambers on May 4, 1960, after 28 days. They were then placed in the same greenhouse as flats FC-2 and FC-5 under the same photoperiod. Flat FC-6 was placed in the cold chamber with lights set for a 10 hour light period. All of the plants in this flat had at least 1 tiller when placed in the chamber. The temperature during the light period was held between 32°F. and 34°F. while the tempera- ture during the dark period was held between 30°F. and 32°F. These plants were removed from the cold chamber on May 20, 1960, after 15 days. They were then placed in the warm greenhouse with flats FC-l, FC-2, FC-4 and FC-5. Flat FC-7 was placed in the cold chamber with lights set for a 10 hour light period on May 20, 1960. All of the plants in the 25 flat had 2 or more tillers plus the main culm when placed in the chamber. The temperature for the first 2 weeks was held between ~32°F. and 34°F. during the light period and between 30°F. and 32°F. during the dark period. During the second 2 weeks the temperature was held at about 20F. colder than the first 2 weeks. The plants were removed from the cold chamber on June 16, 1960, after 27 days. The soil was frozen solid when the plants were removed from the chamber. They were then placed in the same greenhouse as the other flats. The plants from flats FC-l, FC-2, FC-3, FC-4, FC-5, and FC-6 were transplanted into the field on June 16, 1960. The plants were not removed from the peat pots and were Spaced 6 inches apart within rows that were 24 inches apart. The plants in flat FC-7 were transplanted into the field on June 20, 1960, in the same manner. Natural Cold Treatments In this test, NC-I, plants were taken from the field at East Lansing, Michigan, to the greenhouse where all the plants were potted and grown under long day photoperiod. In treatment NC-l, 9 plants were removed from the field to the greenhouse on November 4, 1960. The plants had stopped growing foliage and were dormant at the time they were removed from the field. The weather had been comparatively warm.up to November 4. The mean daily temperature for October was 73.5°F. with a mean low temperature of 52.5°F. There had been only 5 days in which the temperature was below 32°F. and the lowest daily mean temperature for any one day was 33.5°F. 26 Six plants, treatment NC-2, were taken from the field on December 2, 1960, to the greenhouse. The lowest mean daily temperature for the period between November 4 and December 2 was 26°F. on November 30, 2 days before the plants were removed from the field. The average daily high temperature was 56.6°F. with an average daily low temperature of 34.6°F. In treatment NC-3, 12 plants were taken from the field to the greenhouse on January 25, 1961. The ground was frozen at the time the plants were removed from the field. The temperature during December and January was considerably colder than the temperature during November. The mean daily temperature for the period between December 2, 1960, and January 25, 1961, was 23.9OF. for December and 24.4°F. for January 1 to 25. The average low temperature for December was l6.3°F. and for the January period it was l7.5°F. Head Removal Some plants stop producing reproductive buds when they start to produce fruit; however, if the fruits or flowers are removed so that fruit cannot be matured, the plants will continue to produce reproductive buds. Evidently some substance is produced by the developing fruit which inhibits the production of new reproductive buds. This test, HR-I, was made to determine whether or not the development of a seed head on the most advanced culm inhibited the development of seed heads on the other tillers in that tiller group or on the main culms which did not have 7 leaves. 27 In Russian wildrye, the lateral buds in the axils of the first 3 leaves normally deve10p into tillers. When these devel- oping tillers reach the 4 to 6 leaf stage, the lateral buds in the first 3 leaf axils start to develop into new tillers. When these secondary tillers begin to develop, the internode between the parent culm and the first node on the new tiller elongates slightly which sets off the new tiller group from the parent culm. This type of growth results in the tillers normally developing in clumps of 4 tillers (the main culm and 3 tillers) as shown in Figure 2. In this paper each of these groups of tillers is referred to as a "tiller group." The seed heads were removed from 13 plants on the dates shown in Table 2. Each culm which had either a seed head emerged or in the boot was cut off at ground level. All of the heads on any one plant were at approximately the same stage of development at the time when they were removed from the plant. The growing points from the plants with heads removed were compared with the growing points of plants from.which the seed heads had not been removed and were allowed to mature seed. Six of the plants had been grown under short day photoperiod from the time they were brought from the field to the greenhouse on March 9, 1960, and were continued under short day photoperiod until the end of this test which was 4 weeks after the date of head removal. The other 7 plants in the test had been under long day photoperiod and were continued under long day photoperiod until the end of the test. 28 Figure 2. Tiller group of Russian wildrye showing the characteristic 4 tiller group. The culm second from the right is the main culm. 29 Table 2. Head removal data and photoperiod under which the plants were grown prior to and during test. Number of Pot No. heads removed Removal date Photoperiod 19 11 April 5, 1960 LD 20 15 " LD 21 9 " LD 1 25 April 10, 1960 SD 4 IO " SD 12 14 1' so 57 18 April 19, 1960 LD 22 --) SD ) 23 --) SD ) 24 --) SD )...1 43 --) LD ) 44 --) LD ) 45 --) LD 1Number of heads removed not recorded. Field Nitrogen and Plant Disturbance A field fertilizer test, FN-I, was set up to determine the effect of 3 rates of application of fertilizer applied at 4 differ- ent dates at East Lansing, Michigan. The plants to which the fertilizer was applied had been planted in the greenhouse in April and tranSplanted to the field in June, 1960. They were space planted in the field into rows spaced 24 inches apart and the plants were Spaced 6 inches apart within the row. At the time the fertilizer was applied in the fall, the plants were rather uniform in growth and visible development. ail > (A. tall, 5!: 30 The fertilizer applications consisted of ammonium nitrate at the rates of 20, 40 and 80 pounds of nitrogen per acre. The fertilizer was applied in a 2 inch deep furrow placed about 4 inches from the plants. The fertilizer was spread in the furrow and then covered. Fertilizer was applied on August 30, September 7, Septems ber 13, and September 20, 1960. The soil was moist at the time when the first application was made. At the time of the second and third applications, the soil was quite dry but a rain was received Shortly after the third application and the soil was very moist at the time of the fourth application. Each plot consisted of 6 feet of row, or 12 plants. Two rows of untreated plants were left between the treated rows. One plant from each of the 12 treatments and 1 plant from an untreated area were removed from.the field on October 4, 1960, December 2, 1960, and on January 25, 1961. These plants were taken to the greenhouse where each one was divided into 3 segments and planted in 4 inch pots. Other plants for anatomical studies also were taken from the field during the winter. A small section of tillers was removed from.each of 3 plants in each of 12 plots on April 14, 1961, and transplanted into 4 inch pots in the greenhouse in an attempt to get earlier data on the production of heads than would have been possible if the plants had been left in the field. This left 3 or more undisturbed plants and 3 disturbed plants in all plots. Since the removal of the small section of tillers from the plants in the field caused a considerable reduction in the number 31 of heads produced by each disturbed plant, the data were analyzed by the 3-classification method of analysis of variance with 3 plants in each plot. The 3 variables were rates of fertilizer application, dates of fertilizer application, and disturbance of plants. Test FN-II was made to determine the effect of fertilizer on older established plants. Ten of the original plants from Wyoming which were not used in test NP-I were used in this test (see test NP-I for history of these plants prior to March 9, 1960, page 15). These plants had been potted in 8 inch pots containing potting soil on March 9, 1960, and had not received any fertilizer until the start of this test. All plants had produced heads in April of 1960. A trench 18 inches wide and 12 inches deep was dug in the field. This trench was filled with washed sand into which the plants were tranSplanted from the pots on October 8, 1960. They were spaced 24 inches apart in the sand. Plants 31 and 32 each received 134 m1. of 1/2M.Ca(NO3)2 when they were transplanted into the field. Plants 33 and 59 each received 134 m1. of l/2M Ca(NO3)2, 67 m1. of l/2M.KH2PO4 and 67 m1. of l/2M.MgSO4°7H20 when they were transplanted into the field. The other 6 plants, 25, 28, 29, 30, 61, and 62, did not receive any fertilizer. Anatomical Studies A study was made to determine when the growing points in Russian wildrye changed from the vegetative to the reproductive Stage. Sample tillers or tiller groups were taken at various 32 dates to determine the Stage of development of the growing points. Each tiller was carefully examined under a dissecting microscope. The number of leaves per tiller was counted. Primordia that had reached the double ridge stage of development as described by Bonnett (2), Evans and Grover (8) and Purvis (29) were considered as reproductive primordia. The first set of tillers was collected on March 14, 1960, 5 days after the plants used in test NP-I had been brought to the greenhouse and potted. Each sample consisted of one tiller group taken from each plant in the NP-I test. Samples were again taken from these same plants on May 4, 1960, after the plants had headed. As no plants of Russian wildrye-~other than seedlings--were available at East Lansing in 1960, samples of tillers were taken from plants in the field at Laramie, Wyoming, on June 1, 1960. Samples also were taken from the plants which were received from Laramie, Wyoming, on January 20, 1961. Results and Discussion To give a clearer picture of the nature of the plant under discussion, Figure 3 is presented. Under favorable conditions, the growth of Russian wildrye seedlings is very rapid after the first month. Seed planted March 25, 1960, had produced 1 tiller by the end of 4 weeks, April 24, 1960. On June 4, the plant had 17 tillers. Four weeks later, June 30, the plant had 87 tillers and by July 29--18 weeks after planting-~the plant had 166 tillers. Examination of the growing point of freshly-dug plants shipped fromflWyoming and of numerous other plants during the next few months led to the tentative conclusion that a floral primordium was found only after the bud had developed the maximum of 7 leaves. Nitrogen-Photoperiod Three nutrient solutions, in test NP-I, were given to the plants which were brought from the field, divided and planted in 8 inch pots on March 9, 1960. All of these plants had made vigorous growth the previous season and did not appear to be lacking nitrogen at the time they were potted. All of the plants headed, regardless of the treatment given, and the number of heads produced by the plants under each treatment was not significantly different. Since the plants, which did not 33 34 Figure 3. Russian wildrye plants showing typical bunch growth with abundance of basal leaves. Upper photo, taken October 18, 1960, Shows growth of seedlings first year. Lower photo, taken May 20, 1961, shows older plants Spaced 24 x 24 inches. 35 receive any nitrogen from the time that they were potted in March until after heading, produced as many heads as the plants which received either a complete nutrient solution or a nutrient solu- tion with extra nitrogen, it is clear that the quantity and balance of nutrients necessary to produce heads may be present in the plant at the time it became dormant in the fall. This would also suggest that floral differentiation had taken place in the bud before the plants started growth in the Spring. Therefore, nitrogen applied in the Spring of the year may not increase the seed pro- duction for that season. This is in agreement with work reported by Heinrichs and Lawrence (13), Rogler (33), Stelfox, Heinrichs and Knowles (38) and Stitt (39). The length of photoperiod from the time that Russian wildrye started growth in the Spring until it produced heads did not affect the number of heads produced; however, the photoperiod did have an effect upon the heading date. The plants grown under short day photoperiod headed one week later than the plants grown under long day. Both sets of plants in test NP-I when removed from the field to the greenhouse and grown under short and long days initiated reproductive primordia. Photoperiod There was no apparent difference in the number of heads produced per plant between the plants grown under short or long days in test P-II. Also, both the short and long day plants 36 initiated reproductive primordia. Similar results were obtained in test P-III. The length of photoperiod apparently did not control floral initiation in Russian wildrye. Seed Conditioning In the cold treatment of seeds, SC-I, (see page 19 for details) the seed to which one gram of water was added per gram of seed and held at room temperature for 24 hours, then held at 2°C. for 26 days, SC-3, had a much quicker emergence than the other treatments. The results of emergence are listed in Table 3. Table 3. Number of seedlings emerged during 13 days after receiving cold treatments. Number of days after planting Treatment 4 5 6 7 8 9 10 ll 13 SC-l 3 4 5 5 6 6 ' 6 6 SC-2 0 0 8 10 15 15 l7 l7 17 80-3 15 17 18 18 18 18 19 20 20 SC-4 0 2 6 7 9 9 ll 11 12 SC-S (no cold) 0 0 0 l 5 9 9 10 13 The seed which was soaked and held at room temperature for 72 hours and then held at -5°C., SC-l, gave poor total emergence. This poor emergence was probably due to the seed Starting germina- tion before being subjected to the cold. Evidently -5°C. was cold enough to damage the germinating embryo whereas subjecting the seed to 24 hours of 2°C. was not enough cold to stimulate the embryo to give early emergence. All of the seeds which were cold treated 37 gave earlier emergence of seedlings when compared to controls. After emergence there was no apparent difference in the growth and development of the seedlings due to the cold treatments. In the second cold test, SC-II, (see page 20 for details) seeds given treatment SC-6 or SC-7 gave a greater number of seed- lings emerged on the second and third days. Treatments SC-8 and 80-9 did not give more rapid emergence of seedlings than did the untreated seed, SC-lO. It was observed during these cold tests that germination would occur in the seeds stored at 2°C. if the necessary moisture was present. Some of the seeds which were held at 2°C. on wet blotter paper in a petri dish develOped normal coleoptiles and roots after about 35 days. This Slow germination during the cold temperature probably accounted for the rapid emergence of seedlings from these seeds. Even though the seeds in treatments 30-8 and SC-9 were held under high humidity, the seeds tended to dry out during the cold period. There may not have been sufficient moisture present for these seeds to start germination during the cold period which may be the reason that the seeds given treatments SC-8 and SC-9 did not give quicker emergence than the untreated seeds. The number of seedlings emerging on the second through the seventh day for cold test SC-II and the number of seedlings emerging on the third through the seventh day for test SC-III are shown in Table 4. Table 4. Number of seedlings emerged during 7 days after receiving cold treatments. Number of days after planting Treatment 2 3 4 5 6 7 Test 80-11 80-6 5 14 19 19 19 19 SC-7 5 ll 16 16 l6 l6 SC-8 0 7 13 14 15 15 SC-9 0 8 16 16 16 16 80-10 (check) 0 8 l7 17 17 17 Test SC-III SC-ll 7 l7 l9 l9 l9 SC-lZ 4 19 19 19 19 SC-l3 10 l8 l9 l9 19 80-14 8 17 18 l8 l8 SC-15 4 12 15 l7 l7 SC-l6 10 19 19 20 20 80-17 6 18 l9 l9 l9 SC-l8 8 l7 17 18 19 SC-l9 15 19 20 20 20 SC-20 2 l7 19 19 19 SC-Zl 3 13 17 18 19 80-22 8 17 20 20 20 SC-23 (check) 4 18 18 l9 19 30-24 (check) 7 14 16 16 16 39 There was no appreciable difference in rate of seedling emergence between cold treated seeds and untreated seeds in test SC-III. This was probably due to insufficient moisture during the cold period to Start germination. The seedlings from test SC-I and SC-II were transplanted into the field on June 16, 1960. They were spaced 6 inches apart within rows 24 inches apart. The seedlings from test SC-III were transplanted to the field on June 20, 1960. None of the seedlings from cold treated seed produced seed heads during 1960. Seedling Cold Treatments and Natural Cold Treatments The stage of deve10pment of the seedlings which were given cold treatments varied from seedlings having only the main culm to seedlings having 2 or more tillers plus the main culm. Figure 4 shows the seedlings given treatment FC-7 upon removal from.the cold chamber. The seedlings given cold treatments FC-l through FC-6 were transplanted into the field on June 16, 1960. The seedlings given cold treatment FC-7 were tranSplanted into the field on June 20, 1960. All of the seedlings were Spaced 6 inches between plants in rows spaced 24 inches apart. None produced seed heads in 1960 but did produce seed heads in 1961. Sample tillers were taken from all plants in the natural cold trial, NC-I, when they were brought to the greenhouse. Upon examination of the samples under a dissecting microscope, it was found that all the plants contained tillers having 7 leaves and floral primordia. 40 Seedlings in flat FC-7 upon removal from the cold Figure 4. chamber. 41 None of the 9 plants removed from the field on November 4, NC-l, made any regrowth of foliage until after the third week in the greenhouse. They then made vigorous vegetative growth but did not produce any heads. All 6 of the plants taken from the field on December 2, NC—2, started vigorous vegetative growth within 2 days after being brought into the greenhouse but none of them produced seed heads. All 12 of the plants taken from the field on January 25, NC-3, started vigorous growth within 2 days after being brought from the field. All 12 of the plants produced seed heads. Apparently a certain amount of cold temperature was necessary before Russian wildrye plants would produce seed heads. Evidently none of the seedlings had initiated reproductive primordia before given the cold treatment. It is also possible that the seedlings did not get a long enough period of cold to cause deve10pment of seed heads. Head Removal Test Tillers were taken from the plants listed in Table 2 (page 29) 4 weeks after the heads had been removed. These tillers were dissected to determine the Stage of development of the growing points Since none of the plants which had had the heads removed had reproduced any visible beads by the end of the 4 weeks after head removal. Primordia which had developed to the double ridge stage were considered as reproductive. .All of the plants from.which the heads had been removed earlier contained reproductive primordia. However, 42 the reproductive primordia of these plants were no further advanced in reproductive development, as determined by inspection of the primordia under a microscope, than those from plants which had previously matured seed. The maturation of seed heads did not inhibit the develop- ment of reproductive primordia on the other tillers of the plants. Field Nitrogen and Plant Disturbance The number of heads produced by each clonal plant in the greenhouse in this test, FN-I, was added to the number of heads produced by the divided plant (left in the field) from.which the small section of tillers was taken. Adding the heads produced in the greenhouse to the heads produced by the parent plant in the field gave the total number of heads produced by each divided plant. The plants from.which a small segment of tillers was removed in the early spring (April 14, 1961) Shortly after the plants had Started Spring growth were approximately the same size as the plants which were not disturbed. The growth of the dis- turbed plants was much less vigorous than the undisturbed plants as shown in Figure 5. A highly significant reduction in the number of heads pro- duced was caused by the disturbance of the plant roots. The number of heads and the percent reduction in the number of heads produced, in relation to the time of nitrogen application and disturbance, is shown in Table 5. 43 Figure 5. Result of root disturbance. A small section of tillers was removed from each of the 3 plants on the left on April 14, 1961. The plants on the right were undisturbed. 44 Table 5. Number and percent reduction of heads produced in relation to date of nitrogen application and disturbance (division) on April 14, 1961. Date of Undivided Divided Percent nitrogen application plants plants reduction August 30 150 111 26.0 September 7 163 107 34.4 September 13 179 63 64.8 September 20 292 129 55.8 The number of heads produced and the percent reduction in relation to rates of nitrogen application is shown in Table 6. Table 6. Number and percent reduction of heads produced in relation to rate of nitrogen application and disturbance (division) on April 14, 1961. Rate of Undivided Divided Percent nitrogen application plants plants reduction 20 lbs./acre 240 130 45.8 40 lbs./acre 251 129 48.6 80 lbs.[acre 293 151 48.5 The average number of heads produced by the undivided plants for all treatment was 21.78 heads per plant while the average for the divided plants was 11.39, an average reduction of 47.7 percent. The number of heads produced by the divided and undivided plants for each rate and date of application of nitrogen is shown in Tables 7 and 8. The difference in the number of heads produced by the divided plants as affected by the various rates or dates of application of nitrogen was not statistically significant at the 5 percent level. 45 Table 7. Number of heads produced by 3 undisturbed plants per plot in relation to rate and date of nitrogen application. Nitrogen Date of application, 1960 Average number applied per acre 8/30 9/7 9/13 9/20 heads per plant 20 lbs. 39 25 59 117 20.00 40 lbs. 49 64 56 82 20.92 80 lbs. 62 74 64 93 24.42 Average number heads per plant 16.67 18.11 19.89 32.44 Average number heads per check plant 16.08 Table 8. Number of heads produced by 3 divided plants in relation to rate and date of nitrogen application. Date of application, 1960 Nitrogen Average number applied per acre 8/30 9/7 9/13 9/20 heads per plant 20 lbs. 45 31 6 48 10.83 40 lbs. 32 50 ll 36 10.75 80 lbs. 34 26 46 45 12.58 The average number of heads produced by the undivided plants from plots fertilized on September 20 was 32.44 heads per plant as compared with 19.89 for those fertilized on September 13, 18.11 for September 7, and 16.67 for August 30. The difference in the number of heads produced due to date of application of nitrogen was found to be highly significant when the data were analyzed by the analysis of variance method. Since the disturbed plants did not make as vigorous growth as the undisturbed plants, it is evident that the disturbance had an adverse effect upon the plants. However, would these disturbed 46 plants have recovered sufficiently from the disturbance to produce as many heads as the undisturbed plants if other plants had not been nearby? Did the nearby plants compound the damage through competition for nutrients and water? These are questions which need to be answered through additional research. The soil was quite dry when the nitrogen was applied on September 7 and remained dry until September 13 when it rained within a few hours after applying nitrogen on September 13. Rain was received also on September 17 and 19. The soil was quite moist when the September 20 application of nitrogen was made. The plants appeared somewhat wilted during the period between September 7 and 13 but started apparent growth shortly after the rain on September 13. The ammonium nitrate pellets may not have been sufficiently dissolved during this dry period for the plants to take up the nitrogen. If this were true, then the September 7 application of nitrogen would, in effect, be like the September 13 application. Neither Heinrichs and Lawrence (13) nor Rogler (33) reported results from nitrogen applied later than early August. The late fall application of nitrogen may give greater head pro- duction because the plants are making less vegetative growth at the later date and the plant may store more of the nitrogen in the crown and roots instead of using it to make vigorous vegetative growth, thereby having the proper quantity and balance of nutrients present in the plant for head development the next spring. 47 The number of heads produced due to the rate of nitrogen application was not significantly different. This may have been due to the fertile soil in which the plants were grown. In this trial, applying nitrogen at rates greater than 20 pounds per acre did not give significantly higher yields. The production of heads from the undivided plants for the 4 dates and 3 rates of nitrogen application when expressed in percent of untreated plants is Shown in Table 9. It will be noted that the August 30 application gave only a 3.7 perCent greater production than the untreated plants while the September 20 application gave a 101.7 percent increase. Table 9. Production of heads in relation to date and rate of nitrogen application expressed in percent of heads produced by unfertilized plants. Percent Rate of nitrogen Percent Date applied of check1 (lbs./acre) of check August 30 103.7 20 124.4 September 7 112.6 40 130.1 September 13 123.7 80 151.9 September 20 201.7 1Unfertilized plants. There were other factors which may have affected the pro- duction of seed heads in this trial. Did the application of nitrogen to dry soil have an adverse effect upon the plants? Since the plants which received nitrogen applications on September 7 and 13 produced more heads than unfertilized plants, it seems improbable that the application of nitrogen when the soil was dry had an 48 adverse effect upon the plants. Also, did the furrow made beside the plants have the same effect as dividing the plants in the spring? This factor could not be analyzed from the data available. However, removing tiller groups from plants during August and September for anatomical Study did not have an apparent effect upon the production of heads by these plants the following year. Further research needs to be done to determine whether applying nitrogen to dry soil or making a furrow beside the plants in the fall for the placement of nitrogen has an adverse effect upon seed production. In test FN-II, plants No. 33 and No. 59 which received nitrogen on October 8, 1960, after transplanting into the field in sand, produced heads the following Spring. Also, plants No. 31 and No. 32 which had received the same amount of nitrogen applied in a complete nutrient solution produced heads the following spring. None of the other plants which had received no added nitrogen produced heads. The plants in this test were gently removed from the pots and placed in the sand so that the least possible disturbance to the plants would occur. None of the plants in this test had made as vigorous growth as other plants in the field. These plants are shown in Figure 6, shortly after they were transplanted into the field. 49 Figure 6. in the test FN-II in the foreground. from March 9 to October 8 in 8 inch pots without additional fertilizer. Photo taken October 10, 1960, Showing the 10 plants They were grown in soil 50 Anatomical Studies The stages of deve10pment of growing points of Russian wildrye are shown in Figures 7, 8, 9 and 10. The drawings were traced from microscope images with the aid of a microsc0pe drawing tube. The typical, slightly elongated dome shape of a vegetative growing point is Shown in Figure 7. The growing point, as it begins to elongate and start to develop double ridges, is shown in Figure 8. This stage of development occurred when the current seed heads were between anthesis and milk stage of development. Figure 9 Shows a reproductive growing point. The double ridges are quite apparent at this stage of development which occurred at about the time that the current seed heads were matured, which was about the first week of July at East Lansing, Michigan, or about the middle of July at Laramie, Wyoming. A further advanced stage of development is shown in Figure 10 where the Spikelets have started to develop. At this stage of develop- ment, internodes 5, 6 and 7 are just beginning to elongate but each internode is Still not more than l.unn long. The growing point shown in Figure 10 was taken from a very vigorous 4-year-old plant on December 12, 1961, at Laramie, Wyoming. Primordia that had reached the double ridge stage were considered as reproductive primordia. By dissecting out the growing points, it was found that all of the main culms of the sample tiller groups taken from the 30 plants in trial NP-I had reproductive primordia. A head primordium, produced by a secondary tiller, was found in only 2 tiller groups. All of the culms which IFigure 7. Typical vegetative growing points of Russian wildly!” Upper left hand drawing shows a vegetative growing point instead by a developing lesf,an1arged appruinstsly 300 .JIrluiaI‘ v- 'w ‘7’ M rmfir‘v 52 Figure 8. Growing points of Russian wildrye changing to the reproductive stage. The start of double ridges is shown in the right hand drawing. Both drawings are enlarged approximately 100 times. 53 Figure 9. A reproductive growing point of Russian wildrye. The double ridges are clearly evident. The drawing is enlarged approximately 50 times. 54 a. -_—- —.- _ _,,_._____________'_ _‘_.__4 . . Figure 10. A reproductive growing point of Russian wildrye at the beginning of Spikelet formation, enlarged approximately 40 times. 55 had primordia had 7 leaves. All of the other secondary tillers had vegetative growing points and either 5 or 6 leaves. Examination of tillers taken from 8 weeks old seedlings on April 7, 1960, showed that none of the seedlings had repro- ductive primordia. The number of leaves varied from.4 to 6 per tiller. Tiller groups also were taken from seedlings on August 9, . 'P'S‘J; 1961, and the growing points were examined. Reproductive pri- ‘ '.‘_ —‘ mordia were found on the larger main culms, and the smaller main ; culms had vegetative primordia. None of the secondary tillers of these tiller groups had reproductive primordia. Dead primordia were found on tillers taken from second year and older plants on June 12, 1961. These primordia had advanced to the Stage shown in Figure 10 before dying. Further experiments have been designed to determine whether the repro- ductive primordia which do not deve10p into Spikes remain dormant until the following year and then complete development or die. More than 500 tillers were dissected to determine the Stage of development of the growing point. All of the tillers which had 7 leaves had reproductive primordia. No tillers with less than 7 leaves were found to have reproductive primordia. Summary Examination of over-wintering tillers on Russian wildrye plants dug from frozen soil in early spring revealed that floral primordia were present on those tillers and only those tillers that had formed 7 leaves. Further examination indicated that the initiation of new floral primordia occurred on such tillers during July at which time seed was maturing in the Spikes. No combination of exposure of seeds or young seedlings to low temperature, length of day, or nutritional differences induced flowering. Even though an abundance of tillers possessing primordial floral parts were found on plants that had grown for one or more seasons, development of Spikes occurred only on those plants that had been exposed to a considerable amount of Sub- freezing weather. Plants that had received scanty nitrogen fertilization failed to produce spikes under conditions where portions of the same clone headed well with high nitrogen fertilization. Appli- cation of nitrogen at such a time as to avoid excessive fall growth appeared helpful, with that in late September being more beneficial to Spike deve10pment than late August. Mechanical disturbance in the spring of Sturdy field-grown plants was found, in limited experiments, to lead to greatly decreased seed production when compared to adjacent plants that 56 '.\'O 1' rm. 57 were left undisturbed. However, when plants were dug from the frozen soil and subdivided into separate pots, the segments produced Spikes as freely as did similar undisturbed plants. Field competition for nutrients and moisture appears to be a factor in preventing the development of Spikes from previously differentiated floral primordia. Russian wildrye is an erratic seed producer. Nevertheless, floral primordia were found to form on virtually all of the more vigorous tillers after seed was formed on fruiting tillers. The i L'.’ problem appears to be that of inducing these reproductive I 831.13.} primordia to complete deve10pment. Although a considerable period of freezing temperature was found necessary for continued deve10pment, this requirement should be met more than adequately by winter exposure in Michigan or Wyoming. From this series of experiments, it appears that the answer to the problem may be found in adjusting nitrogen nutrition to give vigorous growth and abundant tillering while at the same time avoiding excessive crowding or mechanical disturbance in the Spring. A condition of high nitrogen nutrition at the time the crop went into the winter appeared to be highly beneficial. 10. 11. 12. Literature Cited Benedict, H. M. Effect of day length and temperature on the flowering and growth of four species of grasses. Jour. Agr. R88. 61:661'6710 19400 Bonnett, O. T. The development of the barley spike. Jour. Agr. Res. 51:451-457. 1935. Bula, R. J. Vegetative and floral deve10pment in red clover as affected by duration and intensity of illumination. Agron. Jour. 52:74-77. 1960. Chilcote, D. O. and Bula, R. J. Environmental control of flowering in selected genotypes of orchardgrass. Agron. Abstracts. 1961. Doorenbos, J. and. Wellensiek, S. J. Photoperiodic control of floral induction. Ann. Rev. 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