Agronomy and Crop Sciences Commons^™

Seasonal Variation In Symbiotic Nitrogen Fixation Of White Clover, K Sugawara, T Isawat, Y Yashima, I Ito

IGC Proceedings (1977-2023)

Legumes may supply considerable amounts of nitrogen (N) by symbiotic fixation to the pastures and be indispensable species for inexpensive production of forage. White clover (Tri­folium repens L.) is the most popular perennial forage legume, especially in grazing fields, in Japan. But we have little infor­mation on the actual state of N fixation ability in managed field (Brock et al., 1981; Murphy and Ball, 1985). In this study, N fixation was measured in white clover field during 4 successive years and the seasonal patterns of the activity were investigated in relation with the changes of the atmospheric conditions : …

Dinitrogen Fixation And Nitrogen Transfer In Temperate Legume-Grass Communities, G H. Heichel

IGC Proceedings (1977-2023)

Perennial forage legumes fix atmospheric dinitrogen (N₂) and, in mixed swards of legumes and grasses, may transfer nitrogen (N) to the companion grass (Brophy et al., 1987; Ta and Faris, 1987). The amounts of N₂ fixed by legume-grass mixtures in the temperate North Central U.S. are not known. Further the amounts of N transferred from legumes to com­panion grasses are not known. The purpose of this research was to quantitate N2 fixation of and N transfer in legume-grass swards.

Etude Des Relations Entre Le Deficit Hydrique Et La Fixation D’Azote Chez Le Trefle Blanc, Ch Robin, Liza Shamsun-Noor, D Schontz, A Guckert

IGC Proceedings (1977-2023)

L'alimentation hydrique est un facteur limitant important de la fixation symbiotique chez Jes legumineuses (Pankhurst et Sprent, 1975; Sprent, 1976; Albrecht et al., 1984). Le trefle blanc, ne possedant pas de systeme racinaire puissant, subit des phases de deficit en eau !ors des secheresses estivales. Cette note rapporte le role du facteur varietal dans la tolerance au deficit hydrique du trefle blanc.

Quantifying The Nitrogen-Supplying Capacity Of Legumes To Non-Legumes In Crop Rotations Using 15n, O B. Hesterman, G H. Harris, T S. Griffin

IGC Proceedings (1977-2023)

Economic and environmental concerns are prompting a heightened interest in using forage legumes in crop rotations to provide nitrogen (N) to subsequent non-legume crops. Yet there is a lack of information on the amount or proportion of N from forage legumes available to subsequent crops. Many fertilizer recommendations base legume N contributions on a fertilizer replacement value (FRY), which is the amount of inorganic N required to produce a subsequent non-legume crop yield equivalent to that produced following a legume. Legume N contributions based on FRY methodology typically exceed 100 kg N ha-1 (e.g. Bruulsema and Christie, 1987; Voss and …

Legume Breeding Strategy For Increased Nitrogen Fixation In New Zealand Temperate Pastures, J R. Crush

IGC Proceedings (1977-2023)

The energy level actually achieved at any site in grassland is governed by the mass flow of nitrogen (N) through the biota (O'Connor, 1967). As nitrogen limits pasture production, at all stages of pasture development, the aim of pasture management is to maintain the maximum amount of effective nitrogen in the system (Jackman, 1971). Prospects for increasing symbiotic N fixation in temperate grasslands have been reviewed (Ball and Crush, 1985). Of two strategies, growing more legume or reduc­ing the legumes ability to use mineral nitrogen, the former was favoured. This was because mineral nitrogen is thought to be important, in …

Factors Affecting Isotopic Fractionation During Nitrogen Fixation By Pasture Legumes, S F. Ledgard

IGC Proceedings (1977-2023)

The ¹⁵N natural abundance method for measuring N₂ fix­ation by legumes has compared favourably with other methods (reviewed by Shearer and Kohl, 1986). This method is based on the small difference in ¹⁵N abundance between nitrogen (N) derived from N2 fixation and N derived from soil. The pro­portion of legume N fixed from atmospheric N2 (PN) is cal­culated using :

PN = (o¹⁵Nref - o¹⁵N1egume)/(0¹⁵Nref - B)

where o¹⁵N is the per mil ¹⁵N excess over atmospheric N₂ ; ref is a reference plant which obtains all …

Nitrogen Fixation By "Grassland Kopu" And "Grassland Huia" White Clover As Affected By Nitrogen Regime, S F. Leggard, A M. Eltilib

IGC Proceedings (1977-2023)

During the past 20 years, almost all white clover sown in New Zealand has been« Grassland Huia », which is a medium­small leaved cultivar (Williams, 1987). A large leaved, upright growing cultivar called « Grassland Kopu » has recently become available and this should be better suited for intensive rotationally-grazed pastures. Van den Bosch et al., (1986) measured increased clover growth from Kopu in a mixed clover/grass sward. However, little is known about the relative tolerance ofKopu and Huia to nitrogen (N) fertiliser use. West et al., (1986) measured greater N2 fixation from Kopu than Huia under low and high …

La Definition De La Date Optimale De La Premiere Pature De Quelques Especes Et Varietes De Graminees Fourrageres, B Rutkowska, E Lewicka, A Kolakowska

IGC Proceedings (1977-2023)

La rationalisation du piiturage depend aussi de la date de la piiture, particulierement au printemps, au moment de la pre­miere ou de la deuxieme piiture quand !es tiges floriferes des graminees commencent a se developper (Allerit, 1978 ; Gillet, 1980). On sait que la meilleure periode pour debuter le piiturage se situe lorsque les plantes ont 20-25 cm de hauteur, !es ani­maux mangent mieux et !es pertes par pietinement sont limi­tees. En dehors de cela !es resultats des experiences frarn;aise et suisse (Caputa, 1975; Gillet et al., 1980) montrent qu'a cette hauteur !es jeunes tiges floriferes ont une hauteur de …

Variabilite Interannuelle De La Croissance Printaniere D’Une Prairie Permanente Lorraine Exploitee En Paturage Tournant Intensif, J L. Fiorelli

IGC Proceedings (1977-2023)

La modelisation de la gestion du paturage reclame une description aussi precise que possible des processus biologiques en cause (Hodgson, 1985), notamment en ce qui concerne la croissance de l'herbe. La maitrise des conduites de paturage necessite que l'eleveur anticipe les variations et les perturbations de comportement des couverts prairiaux affectes aux animaux. Cependant, Jes references restent aujourd'hui peu nombreu­ses a propos des prairies permanentes paturees en zone semi­continentale, comme dans le Nord-Est de la France par exem­ple. Pour ces raisons, un dispositif de petites parcelles a ete mis en place en 1983 a Ia station experimentale de I'INRA, a …

The Study Of Litter In Leymus Chinensis Meadow, Guo Jixun, Zhu Tingcheng

IGC Proceedings (1977-2023)

Leymus chinensis meadow is a main type of grassland in the northeast of China and produces a high yield. Leymus chinensis is dominant species in the grassland and is a kind of high-qual­ity grass with rich nutrients. Owing to over utilization for it, there is little litter in the grassland. It causes the degeneration of grassland. Litter plays a important role in keeping ecological balance of grassland. The decomposition and accumulation of litter are key link for guaranteeing material flow and have a great influence on restitution of grassland. The study on litter in grassland is still rare in China, …

Responses Of Root And Shoot Growth Of Cynodon Dactylon To Cutting Frequency And Growth Regulator, C P. West, C A. Beyrouty, E E. Gbur

IGC Proceedings (1977-2023)

Little is known of root growth dynamics of perennial grasses in relation to time of year and vegetative shoot development. Characterizing root growth as influenced by shoot manipu­lation would aid in understanding plant response to manage­ment and environmental variables. Frequency of cutting or grazing and the use of seedhead-suppressing chemicals are two management tools available for manipulating shoot growth. The objective of this research was to study changes in root and shoot growth of bermudagrass as influenced by cutting fre­quency and seedhead suppression.

Etude De La Croissance Des Repousses De Printemps Du Ray-Grass Anglais Apres Divers Stades D’Exploitation Du Premier Cycle, J L. Raphalen, A Margueritat, J Orsini, H Suzineau

IGC Proceedings (1977-2023)

L'etablissement de modeles agroclimatiques de croissance des prairies contribue a !'elaboration de references fiables de production fourragere. Des modeles statistiques simples entre la production du I er cycle de printemps et le cumul des temperatures (Lemaire et Salette, 1981; Raphalen et Le Bris, 1985) et entre la production estivale et l'alimentation en eau (Raphalen et Le Bris, 1985) ont pu etre formules. Par contre, la modelisation de la croissance des repousses de printemps est plus complexe. La structure des repousses du 2e cycle est evolutive et la morphologie du couvert vegetal est tres differente selon le stade d'exploitation !ors du …

Effect Of Nitrogen On Herbage Growth And Intake By Sheep In Continuously Grazed Swards Of Tall Fescue Genotypes, A Mazzanti, G Lemaire, F Gastal

IGC Proceedings (1977-2023)

Relatively little is known about the growth of tall fescue under continuous grazing. Most of reported works about herb­ age production in such a grazing management have been done with perennial ryegrass and with relatively high levels of nitro­ gen fertilisation (Hodgson, 1981 ; Bircham, 1981; Parsons et al., 1983). The effect ot the level N nutrition on growth of a continuously grazing sward has not been yet studied. On intermitently defoliated swards of tall fescue, Gastal & Lemaire (1988) have shown that with non limiting level of N nutrition the increase in dry matter production could be 4 or …

Effects Of Late Spring Grazing Management On Tiller Age Profiles And Summer Autumn Pasture Growth Rates In A Perennial Ryegrass (Lolium Perenne L.) Sward, C Matthew, J X. Xia, J Hodgson, A.C P. Chu

IGC Proceedings (1977-2023)

In perennial ryegrass (Lolium perenne L.) swards large numbers of new tillers are produced shortly after flowering. This high tiller appearance rate is balanced by a high death rate of tillers produced in early spring so that relatively little change in sward tiller numbers occurs (Colvill and Marshall, 1984, Korte, 1986). Tallowin (1982) showed, however, that differences in grazing management can affect the percentage of early spring tillers surviving, and so result in different tiller age profiles in the following summer. This paper reports the results of an investigation of the effects on tiller age profiles and subsequent pasture …

Matric Potential Of Clay Loam Soils On Arid Rangelands Of The Southwestern United States, C H. Herbel, R P. Gibbens

IGC Proceedings (1977-2023)

Precipication is the major climatic factor affecting plant growth on arid rangelands of the southwestern United States. Soil water on floodplain sites is derived from infiltration of pre­cipitation and run-in water from adjacent slopes. We char­acterized the soil matric potential at three floodplain locations, to help understand the functioning of the soil water component of the floodplains ecosystem of arid rangelands.

Physiological Ageing In Young Leaves Of Digitaria Eriantha (Steud), M M. Wolfson, C F. Cresswell

IGC Proceedings (1977-2023)

In a previous paper, Wolfson and Cresswell (1985) demonstrated that single leaf photosynthetic rates measured on successive leaves near the meristematic tip, in plants treated with different forms and concentrations of nitrogen, decreased reaching very low levels after four month's growth, irrespective of the treatment applied. As the leaves were considered to be young and they were not shaded in any way, it was expected that the photosynthetic rate would remain fairly high throughout the growing period. Therefore it was suggested that the leaves underwent some form of programmed metabolic ageing even though they were still structurally and phy­siologically young. …

Performance Of Cartenoid Pigments Of King Gras (Pennisteum Purperum) Mutants, J Lauzan, R S. Herrera, R O. Martinez, R Cruz

IGC Proceedings (1977-2023)

Previous studies from this series have indicated the varia­bility reached in respect to yields and quality of the king grass clones obtained by in vitro tissue culture. The study of the photosynthetic pigments could contribute to explain the performance of these somaclones in respect to their growth and development. Thus, the objective of the pre­sent experiment was to learn the content and variation of chlorophyll a, chlorophyll b and carotenoids.

Nitrogen And Carbohydrate Mobilizations During Regrowth Of Defoliated Lolium Perenne L., A Ourry, B Gonzalez, J Bigot, J Boucaud, J Salette

IGC Proceedings (1977-2023)

It is generally reported that carbohydrate and organic nitro­gen reserves contribute to re-growth of new foliage in perennial grassland species subjected to clipping management. Only few studies are concerned with the comparative pattern of the mobilization, translocation and recovery of carbohydrate and nitrogen reserves during re-growth following defoliation. Davidson and Milthorpe (1966) have suggested that proteins are mobilized to produce energy in the absence of photosyn­thate whereas non-structural carbohydrates are generally con­sidered as the major organic reserves mobilized during re­growth (White, 1973). The objective of this study was to determine the origin of the mobilized nitrogen compounds and to follow …

Using 13c/12/C Ratio To Discriminate C3 And C4 Plants In Grassland, Lin Xiaoquan

IGC Proceedings (1977-2023)

Smith (1971) had determined the delta13C for plant tissue from 104 species representing 60 families. Higher plants fall into two categories, those (C3) with low delta13C value ( 24 %to 34 %), those (C4) with high delta13C values ( 6 % to 19 %). Now this method and its theoretical basis for plant fraction­ation were developed by many studies (O'Leary, 1981 ; Farquhar et al., 1982), and extensively applied to the domain of the ecology (Tieszen, 1987). In this paper, the delta 13C values of plants were determined by spectrometer and C3 or C4 photosynthetic type was discriminated for 27 …

Stand Characteristics Of Irrigated Cocksfoot Regrowth And Leaf Area Increasing, M Duru, A Langlet, S Rouzies

IGC Proceedings (1977-2023)

For grasses, high leaf area index (LAI) extension rate is necessary to intercept much radiation and to increase the growth rate (Gosse et al., 1986). The LAI extension rate depends on stand status just after the cut : tiller density (Nelson and Zarrough, 1981), residual leaf area and reserves level (Smith, 1974), plant nutrition (nitrogen especially). We study the setting up of LAI for vegetative regrowths according to nitrogen nutrition and different stand status : tiller number and size.

Comparison Of Photosynthetic Enzyme Activity And Identification Of C3 Or C4 Plant For 40 Forages Species Growing On Meadow Steppe In The Northeast Of China, Yin Lijuan, Hou Shuhuai, Shi Decheng, Zhu Ling

IGC Proceedings (1977-2023)

Because the plants with different photosynthetic pathways have distinct photosynthetic or physiological features, the environmental conditions they adapted are different. For example, C4 plant is more adaptable to high temperature, high light intensities and arid area than C3 plant. The characters of C4 plants, such as high light saturation point, low CO2 compen­sation point and so on, make them get higher photosynthetic efficiency than C3 plants, their photosynthetic yield and growth rate are generally over C3 plants. Because the characters of adaptability and the distribution are different for the plants with different photosynthetic pathways, according to the change of ratio …

Levels Of Abscisic In Lateral Buds During Regrowth Of Sorghum Biocolor M., H Nojima, S Fuketa, A Isoda, Y Takasaki

IGC Proceedings (1977-2023)

Lateral bud (tiller) development in grasses is important because tillers may contribute to yield of certain cereal and for­age crops. Especially in herbage grasses, lateral bud release after cutting can result in increased yield and persistence. It is required to elucidate the physiologycal mechanisms controlling tillering. Hormonal regulation for bud release in grasses has been studied by some investigators (Langer et al., 1973; Yeh et al., 1976; Sharif and Dale, 1980; Harrison and Kaufman, 1980, 1982; Isbell and Morgan, 1982; Nojima et al., 1985; Woodward and Marshall, 1988; Richard et al., 1988). Cytokinins are recognized as the hormone which promote …

Ryegrass Herbage Yield Components And Their Response To Water Deficit Stress, D J. Barker, A.C P. Chu, C J. Korte

IGC Proceedings (1977-2023)

The response of grassland production (herbage mass) to factors limiting its production, can be considered the collective response of a number of components. Understanding the impact of factors limiting individual components will aid understanding of factors limiting total production. Pre-requi­site to such an analysis is quantification of the contribution of each component to herbage mass. Perhaps even more import­ant are the dynamics (rate of change with time) of these components and their response to factors such as water stress.

The objectives of this study were : 1) to assess the importance of seven components to herbage mass using principle component …

Variability Of Leaf Area Index Extension Rate On Permanent Grasslands, M Duru

IGC Proceedings (1977-2023)

Canopy growth is related to solar radiation intercepted (PARa), (Greenwood et al., 1986; Gosse et al., 1986). The canopy interception efficiency ( i: i = P ARa/P ARc) is related to leaf area index (LAI). In spring, for grasses i: i = 70 % when LAI = 2 (Lemaire, 1985). The faster the LAI extension rate is, the greater the dry matter yield is. We study nitrogen and grass­land type effects, with phosphopotassic soil fertility level and botanical criterion.

Cinteique De La Croissance Foliarie Et Stolonifere D’Un Peuplement De Digitaria Decumbens Au Cours De La Repousse, P Cruz, G Alexandre, H Baudot

IGC Proceedings (1977-2023)

II existe en climat tropical un grand nombre de graminees fourrageres de type stolonifere. Parmi elles on retrouve de nom­breuses especes dans des genres tels que Digitaria, Cynodon et Brachiaria lesquels representent a eux seuls une tres grande proportion des surfaces herbageres des pays tropicaux, dont Jes iles de la Carai:be Dans ces especes, la production est le resultat de la croissanc de d��ux ense?1ble�� d'organes, feuilles et stolons, dans des pro­portions qm vanent fortement en fonction du temps de repousse et des saisons (Salette, 1971; Crespo, 1985). Connais­sant Jes differences dans la valeur nutritive de ces organes (Her­rera, 1979) …

Distribution Des Assimilats Et Fixation D’Azote Chez Le Trefle Blanc: Influence De La Ramification Du Stolon, C Robin, V Guerin, A Guckert

IGC Proceedings (1977-2023)

Les apex de stolon representent des puits majeurs pour le car­bone chez le trefle blanc (Robin et al., 1987). Ce travail vise a definir !'impact d'une ramification sur la repartition des photo­synthetats. Ce puits supplementaire est susceptible d'induire notamment des relations de competition vis-a-vis des autres apex et des nodosites.

Growth And Gas Exchange Of Rhizoma Peanut (Arachis Glabrata Benth.) Subjected To Water Deficit, K A. Albrecht, J M. Bennett, G M. Prine

IGC Proceedings (1977-2023)

Rhizoma peanut (Arachis glabrata Beuth.) is a long lived per­ennial forage legume adapted to well drained soils of Florida and the humid tropics and subtropics that are prone to both long and short term moisture deficits. The nutritive value of rhizoma peanut is similar to that of alfalfa, thus it is an excel­lent supplement to tropical grass pastures. Prine (1983) reported that yields of 11 t/ha are regularly obtained in north­ern Florida and that yield potentials could be greater in areas with longer growing seaso��and well distributed rainfall. The influence of dryught on yield and physiological responses of rhizoma …

The Effect Of Nitrogen Deficiency On Carbon Partitioning In A Tall Fescue Sward, G Belanger, F Gastal, F R. Warembourg

IGC Proceedings (1977-2023)

Intercepted photosynthetically active radiation (PAR), light­use efficiency and assimilate partitioning are three major determinants of crop growth (Charles-Edwards, 1982). Gastal and Lemaire (1988) reported that the amount of intercepted PAR partly explained the differences in aerial DM yield obtained with contrasting N regimes applied to a tall fescue sward. They also indicated that light-use efficiency and assimi­late partitioning were involved in this N effect on DM yield but they could not differentiate between these two growth determ­inants. Very few field studies of the effect of a N deficiency on assim­ilate partitioning in forage grasses have been reported. Most studies conducted …

Etude Des Deux De La Nutrition Azotee Du Trefle Blanc (Trifolium Repens L.): Activite De La Nitrogenase Et De La Nitrate Reductase, D Schontz, C Robin, A Guckert

IGC Proceedings (1977-2023)

L'importance des deux voies de la nutrition azotee (assimila­tion de l'azote combine et moleculaire) du trefle blanc n'a ete etudiee qu'en terme de bilans 15N (Haystead et Lowe, 1977). L'objet de cette etude est de suivre la cinetique des activites de la nitrate reductase et de la nitrogenase au cours du cycle de developpement en presence de differentes concentrations en nitrates.

Effets Di Nitrate Sur La Croissance Et La Fixation D’Azote Chez Le Trefle Blanc (Trifolium Repens L.): Importance De La Souche De Rhizobium, D Schontz, C Robin, D Laurentie, A Guckert

IGC Proceedings (1977-2023)

Des apports d'azote combine sur des associations graminees­trefle blanc provoquent souvent un desequilibre favorable a la graminee. Cet effet peut etre attribue a une moindre competiti­vite de la legumineuse pour prelever l'azote combine (difference d'exploration du sol par le systeme racinaire) mais aussi a une moindre action de l'azote sur la croissance, du fait de !'inhibi­tion de la fixation. L'objet de cette etude est de tester !'influence de la souche de Rhizobium sur la sensibilite de la fixation d'azote et sur !es consequences de cette sensibilite sur la croissance du trefle en presence de differents niveaux de nitrates.