Plant Pathology Commons^™

Effect Of Burning On The Nitrogen Dynamics In An Indian Grassland, M K. Misra, M Malana, B N. Misra

IGC Proceedings (1977-2023)

The atmosphere and soil are possible sources of nitrogen for plant but nitrogen remains inactive until degraded and minera­lised. Fire acts as a mineralising agent. Fire-manmade or natu­ral is prevalent in the upland vegetations and forests of India. Very little work is available on the nitrogen budget of the Indian grasslands especially in the east coast of India. The objective of this study was to assess the effect of fire on the dis­tribution of nitrogen in soil and plant components and its dynamics in a coastal grassland of Orissa.

Relationship Between Fertilizer Nitrogen And Nodulation Of Tropical Legumes, U R. Sangakkara, K B. Attanayake

IGC Proceedings (1977-2023)

Most tropical pastures are fertilized with N, primarily due to the response of grasses which form its major component. Many studies (e.g. Mahon, 1983) report the adverse effects of applied N on nodulation and N fixation of pasture legumes. Thus, with fertilizer N, the role of the legume is subdued due to reductions in N fixation and competitive dominance of the grasses (Atkins, 1984). Nodulation in tropical legumes begin after root develop­ment, and is expidited by enhancing the early growth of the legume. Due to the occurrence of N deficiency termed « N hunger» during early growth of legumes (Atkins, …

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 …