Physical Sciences and Mathematics Commons^™

A Study Of Seed Formation In Alfalfa With Respect To Environmental Conditions And Pollinating Mode, Alena Vachunova

IGC Proceedings (1977-2023)

The influence of pollinating mode and of conditions for seed formation was studied on 30 clones of different genetic constitution. The average yields per plant have changed markedly under the influence of environmental conditions, especially of variable precipitation.

The correlation between the years was positive and significant. The number of flowers forming pods and also the average number of seeds per flower and per pod are in close relation to the seed yield of the individual plants, not only under self-pollination but also under open pollination. In the dry year of 1973, the correlation coef­ficients under open pollination were lower …

The Influence Of Chemical Mutagenics On Self-Fertility Of White Clover (Trifolium Repens L.), Olga Ezhakova, Roza Piskovatskaya, Zinaida Dikareva

IGC Proceedings (1977-2023)

Chemical mutagenics may be applied for ob­taining self-compatible fonns of white clover. Of the mutagenics under study, ethylenirnine at concentrations of 0.01 and 0.03 % proved most efficient. The high degree of self-com­patibility is transmitted and increases in the following generation. The yield of self-compatible forms depends on the initial material chosen.

Variability Of Characters In Populations Of Red Clover Varieties (Trifolium Pratense L.), Mitrogan Smurygin, Nadezhda Bogomolova, Nikolai Kozlov

IGC Proceedings (1977-2023)

Analytical studies into the variation ofeconomic and biological characters have shown that in . late populations the correlations between geno­type and environment were more strongly pronounced than they used to be in early populations. Mean value stability of characters in early populations, as compared to late populations, was obtained to a large extent from the ho­meostasis of individual plant development, whereas late populations were in most cases determined by genotypic homeostasis.

Evaluation Of Some Properties And Characters Of Phleum Pratense L., Jaroslav Janasek

IGC Proceedings (1977-2023)

From 1965 to 1976, 111 varieties of timothy (Phleum pratense L.) have been tested and evaluated at the Roznov Grassland Research Station (Vyzkumna stanice travinafska, Roznov p/R.). Description of characters and properties was made according to the "classifier". Biolog­ical properties, botanical characters, phenolog­ical phases, as well as • seed and forage yields were evaluated in 3-4 harvest years. The characters and properties were evaluated by statistical analysis and laid down in a project for full use in research work and propagation practice. Documentation has been made of  single varities; most of them are kept in the field gene reservoir.

Investigations Into The Initial Material Of Forage Plants, Asfan Yartiev, Zhaneta Yartieva

IGC Proceedings (1977-2023)

Including a large collection of initial material is a major precondition for successful breeding work. This is particularly true for forage plant breeding. Thanks to its vast territory with its different soil and climatic conditions, the Soviet Union disposes of a great diversity of wild-growing forage plant species that has not yet been investigated in full detail. Acad­emician V. R. WJLLIAMS and other Soviet research workers had been the first to investi­gate the collection of forage plants. The further study, collection, and thorough evaluation of this material is attended to by the All-Union Williams Forage Research Institute. Research work conducted …

The Establishment, Screening, And Maintenance Of A Gene Pool Of White Clover (Trifolium Repens L.), W Ellis Davies

IGC Proceedings (1977-2023)

1)-In order to extend the gene pool of a crop plant available to the breeder, it is necessary to collect, screen, assess, and maintain desir­able germ plasm.

2) Collections of white clover (Trifolium repens L.) and other legumes have been made by the Welsh Plant Breeding Station from contrasting geographical areas. Some details of the 1971 expedition to Turkey are re­ported.

3) A considerable amount of variation in growth characters, leaf size, flowering date, and cyanogenic reaction was found.

4) Long-term seed storage experiments have indicated the conditions which favour the maintenance of seed viability. Seeds have maintained c. …

Agronomic Assessment Of The Annual Sub-Species Of Medicago L., E J. Crawford

IGC Proceedings (1977-2023)

The production potential of 171 annual Medi­cago genotypes representing 48 of the possible 52 sub-species was compared under sward conditions. Entry selection was based on superi­ority in seedling vigour, winter herbage pro­duction, seed yield, and range of flowering times. The high production ranking of the com­mercial cultivars illustrates their suitability to the environment. The potential of other non-commercialized sub-species is discussed. The performance of the species dominant in the Mediterranean Basin suggests potential for selection for cultivar development for those agricultural systems.

The World Collection Of The Major Grassland Plant Species Of The All-Union Vavilov Research Institute For Plant Growing, Planton Lubenets, Nina Mukhina, Soya Shutova

IGC Proceedings (1977-2023)

The world collection of perennial grassland plants comprises 12,940 samples of 366 species, thereof 7,094 samples of leguminous plants, 5,286 samples of gramineous plants, and 560 samples of plants growing in arid regions. These samples are tested at experimental sta­tions of the Institute situated in the Noncherno­zem zone, in the northern Caucasus, in Ka­zakhstan, in the Volga area, in West and East Siberia, in the Far East as well as in the Uzbek and Ukrainian Soviet Socialist Republics. The samples were grouped according to the fol­lowing characters: high yields of fresh matter, hay and seeds, resistance to disease, winte_r hardiness, …

Ecological Formations For Seed Production Of Grasses And Legumes In The American Tropics, Augusto Gallardo, Antonio Leone

IGC Proceedings (1977-2023)

Ecological formations of the American Tropics adequate to produce seeds of grasses and legumes are thorny pre-mountainous forest, very dry tropical forest, dry tropical forest, and humid pre-mountainous forest. Previous research concluded in selecting the best species for seed production in each zone and also recommending the most appropriate manage­ment practices to obtain high-quality seed and high yields. To satisfy the requirements of seed for resowing and establishing new areas of pastures in Colombia and Venezuela it would be neces­sary to invest U.S.$ 102,451,674 yearly. F.A.O., I.LC.A., Government research cen­tres, and Agronomy schools have motivated programmes of seed production and …

The Physiological Effects Of Water Stress On Perennial Ryegrass In The Field, E L. Leafe, M B. Jones, W Stiles

IGC Proceedings (1977-2023)

Irrigated and water-stressed swards of perennial ryegrass were compared under field conditions to elucidate the physiological mechanisms which bring about the commonly observed reductions in dry matter (DM) yields caused by drought. Measurements were made during four periods of vegetative growth in the sum­mers of two successive years. The maximum stress developed varied between 62 and 11 6 mm potential soil water deficit. In all but one experimental period, above­ground DM yield was markedly reduced, with corresponding reductions in leaf area index (LAI). The reduction in LAI was caused by a slower rate of leaf expansion> resulting in smal­ler leaves, …

Examination Of Relationship Between Hay Yield, Crude Protein Content And Climatic Index With Alfalfa, Imre Laszlo Kiss

IGC Proceedings (1977-2023)

The correlation between hay yield and climatic indices is very close. In one-, two-and three-year alfalfa stands correlations with the annual climatic index were always closer than those with the climatic index of the growing season. Therefore, precipitations falling outside the growing season have a positive effect on alfalfa crop yields as well. In the future it will thus be more suitable to use the data of annual weather conditions. The climatic factors have a considerable influence on the crude protein content. A very close negative correlation was shown between the respective annual climatic indices and the crude protein content.

The Effects Of Global Radiation Before Harvesting Upon The Digestibility Of The Dry Matter Of Some Grass Species, W Schoberlein, W Lampeter

IGC Proceedings (1977-2023)

Four micro-trials with 6 breeding varieties each of Lolium multijlorum, Lolium perenne and Dac­tylis glomerata (early and late groups) were carried out under field conditions. Neither artificial reduction in daylight by means of a sunshade nor storage of the fresh mass in a dark room with the stems kept in water or else in a plastic bag resulted in abrupt decrease in digestibility as common under conditions of low global radiation. The findings point to the possibility that the composition of the diffuse light on days with poor radiation deviates from the diffuse light under a sunshade on days with …

The Influence Of Temperature, Soil Moisture Content, And Mineral Supply On Growth And Some Fractions Of The Chemical Composition Of Cocksfoot (Dactylis Glonierata L.), A S. Obraztsov, V M. Kovalev, V G. Golovaty, Kh K. Khudyakova

IGC Proceedings (1977-2023)

Experiments in the climatic chamber and in the greenhouse have shown the quantitative dependence of plant growth and productivity as well as of the carbohydrate and nitrate con­tent of Dactylis glomerata L. on temperature, soil moisture conient, and the level of NPK fertilization. Daily means of air temperature of 22 to 23 °C, a soil moisture content coming up to 78-84 p.c. of total moisture capacity, and ap­plication of 60-80 mg N/kg soil (N: P: K ratio 6: 1 : 2) were found to be optimal for plant growth and productivity. Soil moisture deficit raises the nitrate concentration in D. …

Effect Of Soil Water Stress On Biological Parameters Of Guinea Grass (Panicum Maximum Jacq.) And Glycine ( Glycine Wightii), J J. Suarez

IGC Proceedings (1977-2023)

Two experiments were carried out under glass­house conditions to study the effect of soil water stress on guinea grass and glycine. The design was a random block design with four replications. Treatments were: water appli­cation when soil humidity was reduced 25 %, 50 %, 75 % and to wilting point in relation to field capacity. Dry matter yields, leaf number and transpiration efficiency of glycine were significantly reduced (P < 0.001) as were the number of tillers (P < 0.01) and nodules (P < 0.05) with the decrease in available soil humidity. Guinea grass yields (dry) were only reduced when available soil humidity decreased from 75 % to wilting point, glycine being more affected than guinea grass. Root weight, leaf and tiller number and transpiration effi­ciency of guinea grass were not affected by changes in soil humidity. Results suggest a higher drought resistance of guinea grass than glycine since that species made a more efficient water usage, having a more developed root system.

Generative Development Of Perennial Forage Grasses Under Natural And Controlled Conditions, A K. Fedorov

IGC Proceedings (1977-2023)

Both different development types and life spans of perennial forage grasses were found to depend strongly on their own response to light in their tillering phase as well as on their response to vernalization. Possible approaches are suggested by which to accelerate grass breeding, with particular reference being made to the potentials implied in producing several generations in one and the same year. An account is given of a process by which to produce up to five generations of winter­type grasses in one year. Biological foundations are mentioned to control sward structures and to adjust them to desired uses, for …

Relationships Between Some Growth Indices And Dry Matter Formation In Alfalfa And Three Grass Species, Zofia Koter

IGC Proceedings (1977-2023)

The relationships between growth dynamics and growth indices (LAI, NAR, CGR) in alfalfa and three grass species were studied in pot and field experiments. A positive cor­relation was found to exist between leaf area development (LAI) and dry matter growth. The CGR values were especially dependent on nitrogen fertilization and stand density. NAR values did not give any clues regarding produc­tivity.

Yield Formation And Carbohydrate Content Of Lolium Perenne L. Depending On Nitrogen Fertilization And Cutting Height, K D. Robowski, H Kaltofen, O Knabe

IGC Proceedings (1977-2023)

The carbohydrate content of shoots was de­creased by both defoliation and nitrogen fertili­zation. In connection with these responses high nitrogen doses applied immediately after defoliation inhibited plant growth. From these results some implications in regard to intensive grassland farming and to breeding of forage grasses are derived.

Influence Of Nitrogen Fertilization On Certain Morphological Traits Of Festuca Pratensis Huds., Leoppld Solimowski, Lbontyna Olszewska

IGC Proceedings (1977-2023)

Between 1973 and 1975, experiments were laid out with Festuca pratensis (variety 'Motycka') in concrete boxes. Dry matter yield, size and weight of an average tiller, the average leaf blade area as well as the total leaf blade area/ ground area ratio were found to increase as N-rates went up, whilst the number of tillers, the percentual share of leaf blades in dry matter yield and the leaf blade area/leaf blade weight ratio declined.

Some Effects Of Nitrogen Supply On Grass Growth, David Wilman

IGC Proceedings (1977-2023)

The paper summarizes some recent evidence from the Department of Agriculture, Aberyst­wyth, on changes brought about by applied N in field swards of grass. The aspects referred to are the number of tillers; weight per tiller; weights and dimensions of parts of tillers; initiation, appearance and longevity of leaves; and senescence and death of tissue relative to yield.

Relations Between Nitrogen Supply, Nitrogen Content Of Plants, Internal Efficiency Of Nitrogen, And Yield With Forage Grasses, Herbert Kaltofen

IGC Proceedings (1977-2023)

There exists the relation y = y(x) = w(x) [N0 + q(x) x] , where x = nitrogen dose, q = apparent re­covery of fertilizer nitrogen, N0 = amount of nitrogen present in the harvested plant matter in case of x = 0, w = internal efficiency of nitrogen taken up, and y = dry matter yield. The possibilities for improving q by way of plant breeding are rather limited because cul­tivated grasses usually take up almost the entire amount of available nitrogen. On the contrary, improvement of the internal efficiency w by breeding procedures offers much better opportunities. It …

Variation In Transpiration Rate In Dactylis, D Wilson, I B. Abdullah, S A. Trickey

IGC Proceedings (1977-2023)

Rates of water use, photosynthesis, leaf con­ductances, leaf growth, and epidermal and sto­mata! characteristics were examined in Dactylis glomerata L. and D. marina Borrill. Maximum leaf conductances were negatively correlated with epidermal papilla cell height which was greatest in D. marina and least in glomerata. Apparently because of this relationship, marina was able to maintain leaf growth rates longer during a drying pl:riod than was glomerata. D. marina plants were more efficient water users than were glomerata - growth rates of marina plants were greater for a given amount of water than were those of glomerata. Whole plant transpiration rates …

Evaluation Of Environmental Conditions And Physiological Processes Limiting Alfalfa Production Using Simed, R J. Bula, G E. Miles, M M. Schreiber, D A. Holt

IGC Proceedings (1977-2023)

Alfalfa (Medicago sativa L.) herbage accumula­tion, photosynthetic rate, and respiration rate were simulated over a 6-week period under three temperature regimes. The simulations were based on SIMED, a model of the growth and development of alfalfa. Highest herbage yields were noted under the 15 °C regime and lowest under the 25 °C regime. Herbage yields under the 20 °C regime were slightly less than under the 15 °C regime. These yield differences were due to higher photosynthetic rates, lower respiration rates, and a slower maturation rate under the 15 and 20 °C regimes compared to the 25 °C regime.

Formation Of The Biomass Of Long Established Meadow Plants After Sowing, Barbara Rutkowska, Barbara Stanko-Brodkowa, Elizabieta Lewicka, Zofia Debska

IGC Proceedings (1977-2023)

The formation of biomass was investigated in the period from 1971 to 1975 on a productive pasture newly sown up and on an intensively fertilized long-established pasture grazed five times during the growing season. The following layers were taken into consideration: in the above-ground biomass - the stubble (0-5 cm) and the productive crop (above 5 cm); in the underground biomass - the sod (0-5 cm) and the root biomass (5-35 cm). The structure and weight of the biomass, and particularly that of the underground bio­mass, of the newly sown pasture as early as in the third year became similar …

Investigations About The Reserve Carbohydrate Status Of Agropyron Repens Beauv. At Different Levels Of Nitrogen Fertilization Of Grassland, W Seyfarth, O Knade, W Kreil

IGC Proceedings (1977-2023)

Stolons of Agropyron repens were sampled at different dates in a trial fertilized with 0, 60, 120, 240, 480, and 720 kg N/ha for many years. From the carbohydrate fractions determii,ed by means of gas chromatography, the fructosan content, the degree of polymerization, and the content of structural substances are discussed. After heavy nitrogen fertilization the carbo­hydrate requirements of the plants could not be met for some time. Nevertheless, the vitality of plants did not decrease. When controlling Agropyron repens by way of mechanical and crop husbandry techniques, it is necessary to take into consideration the quantity of stolons increasing …

Features Of Regrowth Of Paniculate And Eragrostoid Perennial Grasses, I S. Belyuchenko

IGC Proceedings (1977-2023)

The regrowth of paniculate and eragrostoid grasses is conditioned by their peculiarities of tiller and bud formation. According to their arrangement and role in sward renewal, all vegetative buds of grasses are divided into five groups:

Apical buds of above-ground apogeotropic tillers; Lateral buds of above-ground diageotropic tillers; Lateral buds of above-ground apogeotropic tillers; Buds of tillering zone; Buds of rhizomatic tillers.

These groups of buds differ significantly in their stage of development. The major peculiarity of paniculate and eragrostoid grasses is their ability to regrow from lateral buds of above-ground apogeotropic and diageotropic tillers. The ecological conditions have a …

Tillering In Irrigated Smooth Bromegrass (Bromus Inermis Leyss.) As Affected By Elongated Tiller Removal, James W. Krause, Lowell E. Moser

IGC Proceedings (1977-2023)

A two-year field study at Mead, Nebraska, USA, showed that subsequent tillering was generally increased when 33, 67, and 100% of the elongated tillers were removed in Lincoln smooth bromegrass (Bromus inermis Leyss.). Apical dominance was apparently reduced when elongated tillers were removed and as a con­sequence new tillers elongated. If irrigated smooth bromegrass is grazed in the spring so about 67 % or more of the elongated tillers are removed and subsequent tillering will be in­creased. By removing only 67 % or slightly more of the tillers, remaining leaf area could supply carbohydrates to the small developing tillers.

Net Assimilation And Longevity Of Alfalfa Stands, R A. Moore

IGC Proceedings (1977-2023)

Stand reduction in established fields of alfalfa (Medicago sativa L.) has often been observed. This may be related to an increase in non­photosynthetically active tissue, causing respi­ration to exceed photosynthesis. Net carbon dioxide exchange rate (NCE) per unit leaf area and rate of respiration per gram of forage were determined from plants grown under field conditions. The uptake and evolution of carbon dioxide per plant were measured. The data suggest that the greater root mass of 2-year-old plants does add considerably to the evolution of carbon dioxide by the plant.

Some Results Of Studies On Correlations Between The Size Of The Assimilating Area And The Biomass Production In Medicago Sativa L. And Trifolium Pratense L., F Hrabe

IGC Proceedings (1977-2023)

The dependence of the biomass production upon the size of the assimilating area of Medicago sativa L. and Trifolium pratense L. was confirmed. However, this dependence was not linear in all the cuttings; in Medicago sativa and tetraploid Trifolium pratense the opti­mum values of the leaf area index (LAI) were 5 to 6 m2/m2 and 4 to 5 m2 /m2, respectively. In the second cutting, the highest production of both species was obtained when LAI was smaller by 1 m2/m2 than that of the first cutting. In M. sativa and tetraploid T. pratense the maximum assimilating area (leaves and stems) …

Morphological Characters Associated With Productivity Of Tall Fescue, C J. Nelson, D A. Sleper

IGC Proceedings (1977-2023)

Number of tillers and yield/tiller of tall fescue were similar in their association with forage yield, but were negatively correlated (r = -0.21 **) with each other. Area ofli:3f 6, which was correlated with leaf area expansion rate (r = 0.81 **), was correlated higher with yield/tiller (r = 0.58**) than with tiller number (r = -0.16*). Seeding characters were not strongly associated with number of tillers. In continental climates cool-season forage grasses produce most of their yield during the reproductive growth phase. In order to improve summer and fall productivity we are investi­gating development of the vegetative canopy. RHODES …

The Effect Of Changes In Crop Structure On Photosynthesis, Dry Matter Production, And Chemical Composition Of Lolium Perenne, L Sibma, W Louwerse

IGC Proceedings (1977-2023)

To study the effect of changes in leaf position in perennial ryegrass during the growing season, the leaf position was changed with wide­meshed wire netting in field and greenhouse experiments. CO2 measurements with a mobile unit showed that changing the leaf position from erecto­phile to planophile decreased the carbohydrate production by 30 %, and that proportional recovery of the production occurred when the leaves were replaced in the original erecto­phile position. Throughout a single growing period the nega­tive effect of a planophile leaf position on dry matter production above ground was 10% at the highest. This was associated with lower …