Agronomy and Crop Sciences Commons^™

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.

Leaf Growth In Lolium Perenne L., H Schnyder, S Seo, W Kuhbauch

IGC Proceedings (1977-2023)

Knowledge about the spatial distribution of growth rates within the growth zone of leaves is essential for the study of metabolism associated with the growth process (Silk 1984). Such data have been described for Festuca arundinacea Schreb. during the phase of rapid blade elongation (Schnyder and Nelson 1987, 1988) and Zea mays L. during one developmental stage (Hsiao et al. 1985). No developmental studies appear to have been made. This paper describes the spatial distribution of growth rates within the elongation zone of L. perenne leaves from shortly after tip emergence to shortly before cessation of leaf growth. Special …

Analysis Of The Aerial Part And Roots Of The Lucerne Crop To Improve The Breeding Method, P Rotili, L Zannone, G Gnocchi, S Proietti, C Scotti

IGC Proceedings (1977-2023)

In our research work we consider the lucerne crop as a « system», that means a set of elements with their reciprocal relationships (Rotili 1988). The elements of such a system are the plants ; the whole of their relationships is called the « structure » of the system ; it is expressed by the effects caused by the reciprocal interference among the plants on their mor­phology and physiology. Both these constituents of the system (the plants and the structure) have to be considered by the breeder to improve the lucerne crop. From some hundred experiments established with material genetically …

Relationship Of Leaf Export Of Carbohydrate To Rhizomatous Growth In Panicum Amarum L., D S. Fisher, J C. Burns, D H. Timothy, K R. Pond

IGC Proceedings (1977-2023)

Rhizomatous growth is desirable in pastures, yet many species used for grazing have exceedingly short rhizomes. In damaged pastures, vigorous rhizomes can provide for recovery of areas in which the stand has been lost. In breeding pasture grasses, selecting for high yields in a favorable environment may result in altered partitioning of carbohydrate between shoots and roots to favor above ground growth. In the Panicum genus, this can occur even in spaced plantings in which plants may exceed 2 m in height. The following experiment utilized a high rhizome (HR), an intermediate rhizome (IR), and a low rhizome (LR) accession …

Morphological And Physiological Growth Aspects Of Three Tropical Grasses, J A. Gomide

IGC Proceedings (1977-2023)

Forage plants differ considerably regarding their ability to recover from grazing. Forage regrowth is determined by shoot apex survival (Sheard and Winch, 1966); leaf area (Ward and Blaser, 1961) ; non-structural carbohydrate content (Ward and Blaser, 1961 ; Brown and Blaser, 1965) and tillering potential (Paulsen and Smith, 1969). Little is known about these concepts regarding tropical grasses.

The Morphological Relation In The Panicle Of Panicum Maximum Jacq. Consequences On The Pollination And The Fertility, M Noirot

IGC Proceedings (1977-2023)

In Panicum maximum, the fertility is often low : 9 to 40 % (Warmke, 1951; Javier, 1970). At the Agricultural station of Man (Ivory Coast) - a limit region for natural dispersion of guinea grass -, the same amplitude has been noted. But our observations showed a negative correlation between fertility and panicle length. The study of the spikelet distribution into the sheathed panicle and its factors of variability bring an answer to explain this phenomenon.

Phytochrome Mediated Effects On White Clover Morphogenesis, C Varlet-Grancher, B Moulia, R Jacques

IGC Proceedings (1977-2023)

The balance of a white clover-grass mixture mostly depends on the morphogenesis of white clover under conditions of compe­tition for light (Beinhart, 1963 ; Gastal et al., 1986). Within the recent years, emphasis has been placed on the role of phytochrome as a shade sensor and as a controlling system for the morphogen­esis of light-grown higher plants (Morgan and Smith, 1979). To our knowledge there is only one report on white clover photomorphogenesis available in the literature. This work (Solan­garrachchi and Harper, 1987) deals with the effect of chlorophyl­lian shade on morphogenesis and the effects obtained are some­times contradictory within …

White Clover Root Systems And Their Influence On The Survival Of Perennial Pastures In South Africa, A Smith, D.C W. Goodenough, A.R J. Morrison, Marie F. Smith

IGC Proceedings (1977-2023)

The eastern part of the Republic of South Africa receives a relatively high rainfall, which results in it having a high agricul­tural potential. The quality of natural and cultivated pastures can be vastly improved by the introduction of a legume component. In the areas where pastures are likely to develop, the soils are acid and highly leached. White clover is not normally tolerant of low P, low Ca and high Al soil contents, and due to its nor­mally shallow rooting habit it consequently suffers easily from drought conditions, and therefore has a much reduced pro­ductive period of approximately 30 months …

Effect Of Interspecific Competition On The Development And Early Growth Of Grass Species, U R. Sangakkara, E Roberts

IGC Proceedings (1977-2023)

In a sown pasture, each individual plant tries to gain access to growth resources for its establisment and development. The more competitive species, which generally exhibits more exten­sive seedling growth obtains a greater share of resources, thus modifying the environment within the plant community (Black, 1966). This develops competitive relationships. As competition operates essentially at the individual plant level (Rhodes, 1970), experiments need to study the effect of neighbouring species on the growth and development of a single plant (Mead, 1979). Studies on competition between ryegrass (Lolium perenne), prairiegrass (Bromus catharticus) and cocksfoot (Dactylis glomerata …

Azote Et Equilibre De L’Association Ray-Grass Anglias-Trefle Blanc, J C. Simon

IGC Proceedings (1977-2023)

Bon nombre d'eleveurs s'interrogent sur l'interet des apports d'azote sur les associations ray-grass anglais - trefle blanc, en particulier sur la premiere pousse de printemps. Ces apports conduisent generalement a un desequilibre de !'association en faveur du ray-grass et compromettent de ce fait la perennite du melange. Apres avoir rappele brievement par quelques resultats experimentaux les principales incidences de l'azote sur le niveau de production et sur la composition de la culture mixte, nous analyserons les effets de l'azote sur l'equilibre de !'association a la lumiere des donnees recentes sur la morphogenese des deux plantes.

The Effects Of Coconut Palms On Pasture Understory, R W. Snaydon, D.N S. Fernando, R Sangakkara

IGC Proceedings (1977-2023)

Pastures are extensively grown under coconut palms, and mainly grazed by cattle (Plucknett, 1979). The main advantages of this form of mixed cropping are : (a) diversification of products, (b) additional income, (c) feed for draft animals, (d) weed control, and (e) more rapid nutrient cycling. Surprisingly little information is available on the effects of pastures and coconut palms on each other (Plucknett, 1979) ; even less is known about the mechanisms of competition between them. This study was designed to study the effects of coconut palms on pasture. A trenching technique was used to investigate the effects of below-ground …

Compatibility Of Birdsfoot Trefoil With Tall Fescue Selected For High And Low Leaf Area Expansion Rate, C J. Nelson, K M. Hasson, D A. Sleper, J R. Forwood

IGC Proceedings (1977-2023)

Tall fescue (Festuca arundinacea Schreb.) populations were selected for slow and rapid leaf area expansion rate (Nelson and Sleper, 1983). Daily leaf elongation rate (LER) in the field was increased by 0.30 mm and decreased by 0.53 mm per gener­ation (Nelson et al., 1985), but single-leaf photosynthesis was not affected. Populations selected for high LER had longer and wider leaf blades (Nelson and Sleper, 1983), and lower tiller density, higher weight per tiller, and higher forage yield in veg­etative swards (Nelson et al., 1985) than those selected for slow LER. Zarrough et al. (1983) suggested that tall fescue could …

Determination Of Predictive Zones For The Evaluation Of Herbage Grasses In Cuba, J Gerardo, Hilda Machado, Verena Torres

IGC Proceedings (1977-2023)

Regional studies that evolve a high quantity of environment are made nowadays in order to define the behaviour of a geno­type in different environments, but the workers of introduction programmes can not prove their varieties in all environments. Therefore, it is necessary to select a wide range to represent production conditions. This topic has been studied by several writers (Rambling et al., 1980; Brown et al., 1983). The objec­tive of our study is to reduce test sites due to the high source in income needed in these studies.

Varieties Evaluation Of Lucerne (Medicago Sativa) With Different Winter Dormancy Class, O A. Bruno, R J. Leon, L A. Romero, O R. Quaino

IGC Proceedings (1977-2023)

Lucerne, pure or as a component of mixtures, is the forage more used in many regions of Argentine. In the central part of Santa Fe province it is the basis of feeding in the milk pro­duction systems. The diffusion of this species was done by mean of popula­tions, that at the beginning of this century produced forage of high yield, quality and good persistency. Later, the area ofland cultivated fluctuated, characterized by periods of diminishing and recovery. From 1969 the appearance of Pea aphid (Acyr­thosiphum pisum) gave rise to a critical situation. The solution to this problem was …

L’Effet Du Climat Sur La Production Des Herbages, I Vinczeffy

IGC Proceedings (1977-2023)

Dans les regions arides on peut optimiser la production des herbages par une technologie adaptee au climat, meme dans des sols pauvres. Le climat de la Hongrie est en grande partie sec, Jes sols des herbages sont defavorables, la vegetation est degra­dee et l'effet des engrais est modere. Le rapport entre le climat et la production est presente par Jes donnees du ne traitement d'une experience de 9 ans.

Effects Of Temperature And Photoperiod On The Extension Growth Of Six Temperate Grasses, G.A Van Esbroeck, Jane R. King, V S. Baron

IGC Proceedings (1977-2023)

In western Canada late season pasture yields vary consider­ably among species. During August and early September yields of Bromus riparius and Dactylis glomerata are double that of the more commonly grown Bromus inermis (Knowles and Sonmore, 1985). The importance of leaf area to crop growth rate pnor to canopy closure is well documented (Rhodes, 1973). Two components of leaf area are the final size of leaves and the rate of leaf appearance, with final size of leaves largely dependant on the rate of extension and duration of extension (Edwards, 1967). Since the maturity of a leaf is closely associ­ated with …

C-4 Grass With Legumes: An Energy Efficient Biomass System, C J. Kaiser

IGC Proceedings (1977-2023)

Converting solar energy into biomass is theoretically most energy efficient when species of a high photosynthetic capacity are grown and nitrogen is furnished via symbiotic fixation. Per­ennial warm season grasses with the C-4 photosynthetic path­way outyield perennial cool season grasses that possess less efficient C-3 pathways. Growing a productive perennial warm season grass in sequence with a winter annual legume should increase yearly capture of solar energy per unit area. The different seasonal growth patterns of the winter legume and the C-4 grass should result in less inter-species competition than occurs in traditional cool season grass-legume combinations. As a result, …

Preliminary Rate Of Growth Curves For Legume Based Improved Pastures In The Mid-Altitude Region Of Yunnan Province Of Southern China, J R. Bruce-Smith, Yang Guo-Rong, Huang Bi-Zhi, Li Ji-Xin

IGC Proceedings (1977-2023)

Yunnan Province in south west China is very mountainous and has several major climatic/ecological zones ranging from tropical to alpine but all are dominated by the south Asian monsoonal rainy season. Extensive tracts of hilly depleted range lands occur in the mid-altitude zone (1800-2500 m) that are potentially suitable for developing to improved legume based pastures. Results of investigations as to suitable species and appropriate fertilizers for this purpose have been discussed previously (Mathison et al., 1985 and Wang et al., 1985). The Project has succesfully established model farms at several places throughout the Province and these carry reasonably pro­ductive …

Effects Of Low Temperature On Germination Of Herbage Species Used In New Zealand, J.F L. Charlton, J G. Hampton

IGC Proceedings (1977-2023)

In recent years, New Zealand's grassland industry has been diversified by the farming of different livestock types, and by using a wider range of pasture species. Some of the latter have establishment and growth patterns very different from the herbage species perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), used traditionally by New Zealand farmers. Successful seedling establishment is critical for subsequent successful performance in a pasture. Quality of herbage seed is judged by thousand seed weight, analytical purity, freedom from undesirable weed seed contamination, and high germi­nation capacity. Internationally accepted procedures are used to …