Agricultural Science Commons^™

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 …

Spanish Subclover Ecotypes: Evaluation Under Grazing, L Olea, C Bueno, J Paredes, P Verdasco

IGC Proceedings (1977-2023)

The introduction of australian subclover varieties in the mediterranean environments of Europe has had irregular results (Olea et al., 1985). For this reason, important projects in selection and genetic improvement of subclover varieties adapted to these environments are carried out in Spain, Portu­gal and Sardinia. The selection program used at Badajoz (Spain) has origi­nated ecotypes which have been described by Gomez Pitera (1985) and Gonzalez et al. (1986). These ecotypes have short cycles, high level of hardseedness, high seed production and long flowering period. The final stage in the selection of pasture plants must include the evaluation under grazing. Subclover …

Behaviours Of Annual And Perennial Grass Species In The Same Genus, Y Takasaki, A Isoda, H Nojima, H Oizumi

IGC Proceedings (1977-2023)

A genus including crop species usually has annual and peren­nial species. Although life history is genetically controlled, it is not fully investigated how it is expressed (Nooden, 1980; Woolhouse, 1982). We examined the behaviours of annuals and perennials in the genera Avena, Hordeum, Lolium and Oryza.

Vegetative Growth And Development Of Norwegian Poa Pratensis L. Ecotypes As Influenced By Temperature And Photoperiod, T S. Aamlid

IGC Proceedings (1977-2023)

Temperature and photoperiod are the main environmental factors affecting flower induction in Poa pratensis (Heide, 1980). As all tillers have a juvenile stage, seed yield depends on both number and size of tillers at the end of the previous growth season. Furthermore, most of the seeds are produced on aerial shoots from the rhizome system (Borg, 1974). Thus, the aim of the experiment was to examine the influence of tem­perature and photoperiod on growth and development of various ecotypes.

Herbicide Utilization For Regulation Of Botanical Composition Of Grass Swards, A Lackovic

IGC Proceedings (1977-2023)

In Czechoslovak conditions especially in Slovakia the botan­ical composition of grass swards is for different reasons getting worse and this means the decrease of forage value. As all those swards cannot be improved by complete renovation or by direct strip drilling of productive species into the sward, other possibilities are looked for. One for those is the utilization of herbicides combined with adequate fertilization. Retardation or control of unfavourable species destroy the existing competition which causes the different species succession in the sward. Our aim was to make a positive succession of species in the sward by herbicides utilization and …

Allelopathic Influence Of Certain Pasture Weeds, A E. Smith

IGC Proceedings (1977-2023)

Allelopathy, the direct or indirect effect of one plant on another through the production of chemical compounds that escape into the environment (Rice, 1974) occurs widely in natu­ral plant communities (Gressel and Holm, 1964), and is pos­tulated to be one mechanism by which weeds interfere with crop growth (Gressel and Holm, 1964; Bell and Koeppe, 1962; Muller, 1966). Probably the most significant consequence of allelopathy is the alteration of population densities that affect vegetation patterns in plant communities. The actual and potential roles of allelopathy in agriculture have been exten­sively reviewed (Putman and Duke, 1978; Rice, 1974; Rice, 1979). Generally, …

Economics Of Controlling Weeds Of Permanent Pasture, I Popay, N Barlow

IGC Proceedings (1977-2023)

In general, inedible weeds of permanent pasture reduce pas­ture dry matter available to stock in direct proportion to their cover (Doyle et al., 1984). Translating the effects of weeds on pasture to reductions in animal production is difficult because (i) pasture value can range from zero to the cost of purchased feed (ii) weed effects and pasture value can vary seasonally and interact and (iii) reductions in pasture availability at one time affect later growth (Auld et al., 1987). There have been few direct measurements of effects of pasture weeds on animal pro­ductivity, because of the co.sts involved. However, simulation …

Weed Development In Tropical Sown Pastures, G.E D. Tiley

IGC Proceedings (1977-2023)

The use of artificially sown pastures is relatively recent in the tropics. Grasses and legumes have been evaluated for their value to livestock as well as the more traditional use of resting arable land after cropping. Using the criteria of ease of estab­lishment, production under grazing and botanical stability, a number of species and mixtures were recommended for the humid areas of Uganda (Horrell and Tiley, 1970). Control of weed growth during early establishment and suppression of unsown species subsequently were found to be vital for the success of these tropical ley pastures. The results of monitoring weed development in …

Insect Pests As A Limiting Factor In Green Fodder Production In Lucerne, Their Control And Residual Persistence Of Insecticides, V J. Shivankar

IGC Proceedings (1977-2023)

The green fodder production in lucerne suffers serious loss of about 38 % caused by the insect pests like Empoasca sp., Therioaphis maculata Buck, Aphis craccivora Koch and Hypera variabilis Herbst. under the tropical agroclimatic zone of Bundelkhand-India (Shri Ram and Gupta, 1976). Of these H. variabilis is most serious with regular occurrence and world­wide distribution. No work has been reported on the control aspect of these pests in India, except a few on insecticidal evalu­ation (Shri Ram and Gupta, 1975) and the economic injury level of lucerne weevil (Gupta et al., 1982). Need of the studies on the chemical …

Sitona Hispidulus Larvaw As A Stress On Alfalfa Production, A A. Hower, K T. Leath

IGC Proceedings (1977-2023)

Sitona weevils are pests of various legumes throughout the world. In the United States, the clover root curculio, S. hispi­dulus (F.) is the major species associated with lucerne (alfalfa) Medicago sativa L. This insect has until recently remained obscure as a pest of this major forage crop. However, a recent trend in premature decline of alfalfa has prompted further investigation of this insect/legume interaction. Godfrey and Yeargan (1987) and Hill et al. (1969) indicated that S. hispi­dulus reduced alfalfa production. While adults S. hispidulus feeding on the foliage is of little consequence, it is the associ­ation of larvae with …

Resistance To Plant Parasitic Nematodes In Ryegrasses And White Clover, R Cook, K A. Mizen

IGC Proceedings (1977-2023)

Field and glasshouse experiments indicate that several nematodes damage ryegrasses and white clover (Cook and York, 1985). Populations of these nematodes under grassland are often at potentially damaging densities. Several nematode species of long-term grassland have co-evolved host relationsh­ips in which host resistance is likely to have been selected. This is of direct practical relevance to the control of three nematodes, widespread in England and Wales: the root-knot nematode (Meloidogyne naasi) on ryegrasses; and the stem nematode (Ditylenchus dipsaci) and cyst nematode (Heterodera trifolii) on white clover. Our objectives have been, first, to identify resistant …

The Effect Of Redlegged Earthmite (Halotydeus Destructor) On Legume Productivity, D J. Gillspie, D A. Nicholas

IGC Proceedings (1977-2023)

Redlegged earthmite (Halotydeus destructor) (RLEM) is a

serious pest of legume-based annual pastures in southern Australia. Observations throughout Australia show that every year they cause both mortality and growth retardation in emerging pastures in autumn, and are also responsible for reduced seed set in annual legumes in spring (Allen 1986, Norris, 1948). The most common legumes in areas where RLEM occur, are annual Trifolium species, especially T. subterraneum (subclover). However, the recent development of M edicago polymorpha and M. murex for use on acid soils together with the wider use of Ornithopus compressus, has resulted in alternative hosts for these …

Resistance In Cynodon Dactlyon To Spodoptera Frugiperda: Influence Of Strain And Dietary Conditioning, S S. Quisenberry

IGC Proceedings (1977-2023)

The most important warm-season perennial grass in the southern United States is bermudagrass (Cynodon dactylon [L.]). Fall armyworms (Spodopterafrugiperda [J.E. Smith]) are the most damaging insect pests of bermudagrass. Conse­quently, researchers have evaluated improved bermudagrass varieties for resistance to fall armyworm (Leuck et al., 1968; Lynch et al., 1983; Quisenberry and Wilson, 1985; Jamjanya and Quisenberry, 1988). Comparison of results from these studies have been contraditory, whereas Leuck et al., (1968) and Lynch et al., (1983) reported Tifton 292 to be extremely resistant (100 % larval mortality) to fall armyworm, Jamjanya and Quisenberry (1988) found it to have …

A Methodology For Evaluation Of Host Plant Resistance In Brachiaria To Spittlebug Species (Homoptera: Cercipidae), L Lapointe, G Arango, G Sotelo

IGC Proceedings (1977-2023)

Previously underutilized lowlands in tropical America are increasingly being used to produce meat and milk largely due to Brachiaria Griseb., an introducea genus of East African grass. Brachiaria is well adapted to infertile, acidic soils with high aluminium saturation. It is estimated than 16 million hectares have been planted to B. decumbens Stapf and B. humidicola (Rendle) Schweick in Latin America (Toledo and Nores, 1986). The various genera and species of spittlebugs native to the neotropics are the principal biotic factor limiting utilization of Brachiaria as forage in Latin America. Spittlebugs are capable of causing severe damage to susceptible …

Some Effects Of Diseases And Pests On Seed Production In White Clover, And Their Control, M J. Foulkes, B C. Clifford

IGC Proceedings (1977-2023)

The UK market for seed of white clover (Trifolium repens L.) cultivars is in the order of 1,000 t within an EEC total of some 3,500 t. Although high yields of around 500 kg ha-1 can be achieved, yields are extremely variable (Hides, Lewis and Mar­shall, 1984) and this may be due in part to pathogenic attack. The results reported here are of a field experiment where dis­eases and pests were controlled by pesticide applications in plots grown under two simulated seed production man­agements.

Feeding Sites Of Sitona Hispidulus Larvaw As Infection Foci For Fusarium Oxysporum F. Sp. Medicaginis In Alfalfa Roots, K T. Leath, A A. Hower

IGC Proceedings (1977-2023)

Fusarium wilt of alfalfa (Medicago sativa L.) was first described in 1927 (Weimer, 1928) in the United States and has since been reported from many other areas of the world. The causal agent is Fusarium oxysporum Sehl. f. sp. medicaginis (Weimer) Snyd. & Hans. Shoots of infected plants become yellow and wilt ; often only one side of the plant is affected. The outer root xylem tissue turns reddish brown, and infected plants usually die within one season (Leath et al., 1988). The fungus is soil-borne, survives in organic debris, and can persist up to 10 years as chla­mydospores …

Non-Chemical Control Of Some Disease And Pests In Red Fescue And Kentucky Bluegrass Seed Production, B Cagas

IGC Proceedings (1977-2023)

Diseases and pests are one of the main problems in grass seed production in Czechoslovakia. The silver top (white head) caused by the bug Leptopterna dolobrata L. and the ergot [Cla­viceps purpurea (Fr.) Tu!.] have an effect upon seed quantity and quality. In some years the leaf diseases (rusts, powdery mil­dew, spots) can play an important role in the seed ripening. The chemical control may leads to some problems. The effect of burning in two different periods (summer, spring) and the close cutting were compared in red fescue (Festuca rubra L.) and Kentucky bluegrass (Poa pratensi …

White Clover Yield, Quality, And Persistence : Insecticide, Fungicide, Nematode, And Virus Effects, G A. Pederson, G L. Windham, M M. Ellsbury, M R. Mclaughlin, R G. Pratt, G E. Brink

IGC Proceedings (1977-2023)

White clover (Trifolium repens L.) is the most important for­age legume for perennial pastures in the southeastern United States. Commonly, white clover stands decline within 2 to 3 years after seeding. This decline has been reported to be due to many factors including fungal diseases (Graham et al., 1961 ; James et al., 1980) insects (Graham et al., 1961 ; James et al., 1980), viruses (Kreitlow et al., 1957; Barnett and Gibson, 1977), and root-knot nematodes (Baxter and Gibson, 1959). No studies have evaluated effects of combinations or interac­tions of these factors on white clover growth in the field. …

La Lutte Contre Les Rouilles Du Ray-Grass Anglais Porte-Graine, H Clinkspoor, G Sicard

IGC Proceedings (1977-2023)

Les cultures de ray-grass anglais porte-graine couvrent envi­ron chaque annee en France 2800 hectares, soit un peu mains de 20 % des surfaces nationales toutes graminees confondues. Une enquete realisee sur l'etat sanitaire de ces cultures avait revele qu'elles sont souvent attaquees par des rouilles au debut de l'ete. Quatre rouilles peuvent ainsi etre rencontrees : la rouille cou­ronnee provoquee par Puccinia coronata est la plus frequente ; la rouille noire (P. graminis), la rouille brune (P. loliina) et la rouille jaune (P. striiformis) peuvent egalement se rencontrer. En conditions climatiques favorables, Jes cycles d'infection …

A Multi-Disciplinary Approach To Anthracnose Diseases Of Stylosanthes In Australia, D F. Cameron, S Chakraborty, R D. Davis, L A. Edye, J.A G. Irwin, J M. Manners, I B. Staples

IGC Proceedings (1977-2023)

Breeding Stylosanthes for resistance to anthracnose diseases in northern Australian pastures is complicated by extensive pathogenic variation in the fungal pathogen, Colletotrichum gloeosporiodes. We have put considerable emphasis on epidemiological studies in an attempt to devise optimal strategies for the use of resistance genes in our selection and breeding programs. In addition, techniques of molecular biology are being used to investigate prospects for the use of genes from novel sources and to study the genetics of virulence in the pathogen.