Agricultural Science Commons^™

Advances In Endophyte Research. Progress And Priorities In Temperate Areas, L. R. Fletcher, H. S. Easton

IGC Proceedings (1977-2023)

Fungal endophytes infect a large number of temperate grass species, genera and tribes (Leuchtmann and Clay, 1997). The majority of these systemic endophytes fall into the genus Epichloe or the closely related Neotyphodium genus.

The asexual Neotyphodium endophytes are asymptomatic, never emerge from between the host grass cells, and are only transmitted vertically, via seed of the host plant. They are believed to have derived from the Epichloe endophytes, (Bacon and White, 2000; Schardl and Wilkinson, 2000) which do emerge from their intercellular habitat and form stromata around the emerging seedhead of their host. This is manifested as the choke …

Advances In Rhizobial Research – Progress Priorities In Temperate Areas, Angela Sessitsch

IGC Proceedings (1977-2023)

Rhizobia are well known for their capacity to establish a symbiosis with legumes. During this symbiosis the bacteria inhabit root nodules where they reduce atmospheric nitrogen and make it available to the plant. Biological nitrogen fixation (BNF) is an important source of nitrogen and the various legume crops and pasture species often fix as much as 200-300 kg nitrogen per hectare (Peoples et al., 1995). Globally, symbiotic nitrogen fixation has been estimated to amount to at least 70 million metric tons of nitrogen per year (Brockwell et al., 1995). Furthermore, in many cases nitrogen fertilizers are not efficiently used by …

The Legume – Rhizobia Symbiosis. Does It Vary For The Tropics Relative To The Mediterranean Basin?, J. G. Howieson, A. Mcinnes

IGC Proceedings (1977-2023)

Symbiotic N fixation from legumes is one of the most important biological processes on the planet. It currently provides the majority of the N requirement in agriculture, yet will have to double if cereal crop production is to meet world demand by 2020 (Kennedy and Cocking 1997). To effectively harness the value of biological N fixation from legumes we need to more fully understand G² x E; where G refers to the genotypes of both the legume (G_l) and its microsymbiont (rhizobia; G_r), and E refers to the edaphic environment in which the symbiosis is …

Advances In Forage Legumes: Shrub Legumes, M. H. Shelton

IGC Proceedings (1977-2023)

Forage tree legumes benefit agriculture through their multi-purpose contributions to livestock feeding, to productivity of farming systems, and to protection of the environment.

Of the several hundred forage tree legume species regarded as having potential for forage only c. twenty are in common use. These are listed together with their agroecological range and tolerance of adverse environments including acid soils, cool temperatures, low rainfall, poor drainage and high salinity. The value of many species to ruminants is limited due to low nutritive value arising from low protein availability and low acceptability caused principally by high condensed tannin content. Only 10 …

Alfalfa, J. H. Bouton

IGC Proceedings (1977-2023)

Cultivated alfalfa or lucerne (Medicago sativa spp. sativa) is the most important forage legume in the world with approximately 32 million hectares cultivated mainly in the temperate regions of both the northern and southern hemispheres. Intensive research has been conducted on the management and physiology of the crop and a major seed industry has developed world wide. Since insect and disease pests are numerous in alfalfa, development of cultivars with the proper fall dormancy and a broad genetic base for pest resistance has been pursued in order to provide increased adaptation, persistence, and yield. There has been a …

Carbon And Nitrogen Isotopic Discrimination In Alfalfa For High Yield And Quality Forage, W. S. Oliveira, P. P. A. Oliveira, M. Corsi, S. M. Tsai

IGC Proceedings (1977-2023)

Biological nitrogen fixation and assimilation of CO₂ can be indirectly monitored in alfalfa (Medicago sativa L.) through the variation of the stable N and C isotopes in the plant (Δ values). Such measurements result in a simple, non-destructive and reliable method for identification of alfalfa cultivars of high yield and nutritional quality. A program for selection of 12 alfalfa cultivars under field and controlled conditions (lysimeters) included determination of biomass and N accumulation. Under controlled conditions yields ranged from 1.77 to 2.47 ton/ha/month (Pioneer 5312 and WL-605) and N2-fixed varied from 77.43 to 84.01% for total N (Brazilian …

Stolon Growth And Its Morphological Components In White Clover (Trifolium Repens L.) Cultivars, Omar Scheneiter, E. M. Pagano

IGC Proceedings (1977-2023)

A trial was performed to study the seasonal changes in stolon growth and its morphological components in four white clover cultivars, in the north of Buenos Aires Province, in Argentina. Stolons were tagged in four seasonal measurements periods per year, during two consecutive years. Leaf, stolon and flowerheads weights were recorded at regular intervals in each measurement period and total stolon growth was calculated. Differences among cultivars were found in stolon growth and its morphological components in most of the measurement periods. In spring and summer, differences among cultivars in stolon growth were related to flowering quantity and earliness, and …

Dry Matter Production Of Shoots And Root Density Of Two Cultivars Of Lablab Purpureus (L.) Sweet, L. R. De A. Rodrigues, T. J. D. Rodrigues, A. K. B. Ramos, D. G. De Quadros

IGC Proceedings (1977-2023)

This experiment was conducted in green house conditions to evaluate the DM accumulation in the shoots and in the roots of two cultivars of Lablab purpureus (L.) Sweet. A 2x3 factorial (two cultivars and three evaluation dates) was conducted according to a randomized complete block design with four replications, being the cultivars Highworth and Rongai evaluated at 42, 56, and 70 days after seedling emergence (DASE). The results indicated that the cvs. Highworth and Rongai have the same pattern of DM accumulation in the shoots. In the upper layer of the soil (0-0.20 m) it was found 38.83% and 43.64% …

Yellow-Flowered Lucerne (Medicago Falcata L.) - A Potential Forage Legume For The North, T. Mela, H. Ihamäki, M. Matilainen

IGC Proceedings (1977-2023)

The suitability of yellow-flowered lucerne (Medicago falcata L.) for forage production under the northern conditions was studied in a mixture sward with timothy (Phleum pratense L.) in field trials in South Finland for four years from 1995 to 1998. Through the first three winters lucerne stayed unharmed. In June and July lucerne grew vigorously, but in August little. The total seasonal yields were highest in the second and the third year of harvesting, up to 10 t DM ha^-1. In the winter 1997-1998 , winter damages killed 21 to 38 % of lucerne plants, and resulted …

Role Of White Clover In The Improvement Of Economical Efficiency Of Feeds From Grasslands, P. Goliñski

IGC Proceedings (1977-2023)

The aim of the research was to analyse the role played by white clover in the improvement of economical efficiency of feeds obtained from permanent grasslands. The influence of the proportion of white clover in the pasture sward on unit production costs of yield, energy and crude protein and the profit threshold in milk production was analysed taking into account three white clover cultivars, nitrogen fertilisation, irrigation and overdrilling. The investigation procedures employed the author’s own calculation models elaborated in optimisation programs based on production conditions found in dairy farms in the region of Wielkopolska. It was proved that the …

The Use Of Cafeteria Trials For The Selection Of Desmodium Ovalifolium Genotypes, Axel Schmidt, R. Schultze-Kraft, B. L. Maass, C. E. Lascano

IGC Proceedings (1977-2023)

For the selection of tropical legumes which contain anti-nutritive components such as tannins, relative acceptability of genotypes to ruminants is of particular importance, since these plant components may influence selective grazing behaviour and subsequent animal productivity. Plant-animal interactions are not predictable from laboratory analyses. Involving grazing animals through the conduction of relative-acceptability (=cafeteria) trials at early stages of the germplasm selection process might therefore provide a convenient tool to adjust and confirm genotype selection based on laboratory quality analyses data. As part of a multilocational germplasm evaluation project, cafeteria-experiments were conducted at two contrasting environments in Colombia with a core …

Stolon Mass And Classes In White Clover (Trifolium Repens L.) With Two Soil Water Availability Levels, Omar Scheneiter, E. M. Pagano

IGC Proceedings (1977-2023)

Two trials were carried out to study the stolon mass and classes in white clover (Trifolium repens L.) under two soil water availability levels in summer. In each trial, treatments were two white clover cultivars. From December 15^th to February 15^th in 1993/94 and again during the same period the following year, white clover was grown under 30 to 70 % (Forced water uptake) or 85-to100 % (Maximum water uptake) of field capacity. Every two months, throughout two years, total stolon mass, and buried, superficial, and aerial stolons were measured. Differences between cultivars were detected in stolon …

Morphological Description Of Selected Pigeonpea (Cajanus Cajan (L.) Millsp.) Lines, Rodolfo Godoy, F. H. De Souza

IGC Proceedings (1977-2023)

Seventeen pigeonpea pure line accessions selected for desirable forage traits and three commercial cultivars were described according to morphological characters. The following descriptors were used: growth habit, plant height, number of primary and secondary branches, stem color and thickness, leaf shape and hairiness, flower base and second color, pattern of flower streaks, flowering pattern, immature and mature pod color, pod form and hairiness, seed color pattern, base and second seed color, seed eye (region around hilum) color and seed shape and width. Each individual line and cultivar was satisfactorily distinguished from the others by the chosen characters.

Improvement Of Rose Clover Winter Forage Production, Gerald R. Smith, F. M. Rouquette Jr.

IGC Proceedings (1977-2023)

Rose clover (Trifolium hirtum All.) is a winter annual forage legume that has potential for increased use in the U.S. southern region. New cultivars of rose clover are needed with the combination of cold tolerance, winter forage production and full bloom date of late April. Crosses were made between two early flowering cultivars and one late flowering rose clover cultivar. The F₂ and F₃ generations from these crosses were evaluated in northeast Texas for winter growth, cold damage and date of flowering. Fourteen F₃ lines, out of 37 selected F2 parents, showed large increases (>100%) …

Evaluation Of Brachiaria Brizantha Ecotypes Under Grazing In Small Plots, Valéria P. B. Euclides, Cacilda B. Do Valle, Manuel C. M. Macedo, M. P. Oliveira

IGC Proceedings (1977-2023)

An intense search for new cultivars amongst recently collected and introduced ecotypes from Africa is in effect since 1988, at the National Beef Cattle Research Center, of the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle). After agronomic evaluations of a large collection, 21 ecotypes were pre-selected for multilocational trials and from these, eight were elected for evaluation under grazing. The objective of this trial was thus to evaluate the persistence and carrying capacity of these eight new Brachiaria brizantha ecotypes after two years of grazing. The experimental design was a randomized complete block with nine treatments and two replicates. The …

In Vitro Propagation Of Pennisetum Purpureum Schum., M. M. G. Karasawa, J. E. B. P. Pinto, A. V. Pereira, José C. Pinto, F. G. Silva

IGC Proceedings (1977-2023)

A protocol is described for rapid multiplication of elephantgrass (Pennisetum purpureum Schum.) through shoot tip culture. The plant growth medium consisted of basal medium of Murashige and Skoog (MS) and vitamins Wood Plant Medium (WPM). The medium was supplemented with 0.00; 4.44; 8.88; 13.32 and 17.76 μM of benzylaminopurine (BAP). The elephantgrass was micropropagated by axillary shoot proliferations. Maximum propagule proliferation occurred on Murashige and Skoog (MS) medium enriched with 4.4 μM benzylaminopurine (BAP), resulting an average of 4.0 shoots per explant from cultivar Mineiro and 2.19 from cultivar Pioneiro. The best height and root plantlets were obtained with …

'Stay-Green' And Non-'Stay-Green' Perennial Ryegrass In Field Swards With Different Intervals Between Cuts, D. Wilman, K. R. Kennedy, M. O. Humphreys

IGC Proceedings (1977-2023)

The purpose of this study was to investigate the effect of the 'stay-green' character, originally introduced into perennial ryegrass (Lolium perenne L.) for amenity purposes, on herbage yield, N concentration and colour in field swards of 'stay-green' forage ryegrass managed in different ways for agricultural use. The conclusions were that the introduction of the 'stay-green' character (1) confers greater greenness only at some times of year and only when there has been a sufficiently long period of regrowth, (2) is expressed only in older, as distinct from young, tillers, (3) reduces herbage yield, particularly when a long interval is …

Agronomic Evaluation Of Alfalfa Cultivars In Rio Grande Do Sul, Brasil, J. C. De Saibro, R. Battisti, T. M. S. Freitas

IGC Proceedings (1977-2023)

From April 1995 to June 1998, thirty five alfalfa (Medicago sativa L.) cultivars (cvs.) were evaluated in a field trial at the “Depressão Central” ecoclimatic region, in southern Brazil. Two years after sowing, 30 cultivars were excluded from the test due to their poor overall agronomic performance, mainly low forage DM yields. The remaining cultivars: Crioula (local genotype used as a check), Victoria, Rio and P 30 are hay-type cultivars while Alfagraze is a grazing-tolerant type. Twenty-two harvests were made and no significant differences were found for total DM yields among cvs. Crioula, Victoria, Rio and P 30; however, …

Switchgrass For Biomass Production, Monroe Rasnake, D. Parrish, Garry D. Lacefield, D. Wolf

IGC Proceedings (1977-2023)

Six cultivars of switchgrass (Panicum virgatum) were established in 1993 at Princeton, Kentucky, USA. Two harvest systems were used: two cuttings per year in mid-June and November and one cutting per year in November. Biomass yield and stand survival were evaluated. Lowland cultivars produced more biomass than upland cultivars in both cutting managements. Upland cultivars did better in a two cut system while the other cultivars showed little difference. Excellent stands of all cultivars were maintained under both cutting managements.

Evaluation Of Paspalum Spp. With Adaptation To Poorly Drained Soils In The Tropical Americas, Michael Peters, B. Hincapié, P. Avila, C. E. Lascano

IGC Proceedings (1977-2023)

A collection of Paspalum accessions obtained from Brazil was tested for their adaptation to poorly drained soils. Three accessions were selected based on their DM production and nutritive value. Productivity and quality of these three accessions was stable over the periods of maximum and minimum rainfall, giving potential for continuous forage supply throughout the year in the tropical Americas. Grazing trials for the selected accessions are underway.

Intake Characteristics And Performance Of Contrasting Grass Varieties Continuously Stocked With Sheep, R. J. Orr, J. E. Cook, R. A. Champion, A. J. Rook

IGC Proceedings (1977-2023)

Fifteen intermediate-heading perennial ryegrass (Lolium perenne) varieties were grazed by sheep under continuous variable stocking management. Mean daily grass dry matter intake per ewe was positively correlated with liveweight gain per ewe (r = 0.63) and per ha (r = 0.58) over an 8-month grazing season. Daily intake was not correlated with grazing time (r = 0.12) but was positively correlated with instantaneous dry matter intake rate (r = 0.75). Breeding varieties with high intake rate characteristics should allow increases in the contribution of grazed grass to grassland-based livestock farming. There is now a …

Drought Tolerance Of Interspecific Hybrids Between Trifolium Repens And Trifolium Ambiguum, A. H. Marshall, M. T. Abberton, T. P. T. Michaelson-Yeates, I. Rhodes, A. Williams

IGC Proceedings (1977-2023)

Hybrids between the stolonifeous white clover (Trifolium repens L., 2n=4x=32) and rhizomatous Caucasian clover (T. ambiguum M.Bieb, 2n=4x=32) have been produced. A backcross 2 (BC2) generation with white clover as the recurrent parent combines the growth habit of both parent species with the objective of increasing the persistency of large leaved T. repens varieties under grazing. T. ambiguum is more drought tolerant than T. repens. The drought tolerance of the hybrids in comparison with the parental species was compared in deep soil bins over a four week drought cycle. Soil moisture content, leaf relative water content …

Variability For Nitrogen And Phosphorus Uptake Among Timothy Genotypes, Réal Michaud, Gilles Bélanger, A. Brégard

IGC Proceedings (1977-2023)

Cultivars of timothy (Phleum pratense L.) with high N and P use efficiencies are required to reduce costs of production and risks of N and P pollution, and to meet the nutrition requirements of high producing animals. This field study aimed at comparing, (under three N rates) the relationship between DM yield, N uptake, and P uptake of 27 timothy half-sib families, plus the cultivar Champ as a control (Dry matter yield), N and P uptake increased with increasing N rates. Genotypes also differed for DM yield, N and P uptake. For a given DM yield, the genotypes had …

New Stylosanthes Guianensis For Tropical Grasslands, Bela Grof, Celso D. Fernandes, A. T. F. Fernandes

IGC Proceedings (1977-2023)

Hybrid stylos (Stylosanthes guianensis var. vulgaris x var. pauciflora) with durable, quantitative resistance to anthracnose, mid-season harvest maturity date (early-July), high DM and seed yields have been selected at the Embrapa Beef Cattle Research Center, Campo Grande, Brazil. The hybrids displayed improved forage traits in Brazil, the native habitat and major center of diversity of the species and its pathogen, as well as in vastly different ecosystems. Dry forage yields and anthracnose resistance of superior selections and their composites were equal, in some instances, significantly better, than those of cv. Mineirão in multilocational trials situated in the Cerrados from …

Research On Forage Quality: Progress And Priorities, J. A. Milne

IGC Proceedings (1977-2023)

A broad definition of forage quality is used and the purposes for which research on forage quality is undertaken currently are outlined. These range from research that provides simple measurements that describes the forage quality of a commercial product to research on forage quality to improve understanding of digestion processes. Much of the research in the last decade has related to improving predictive measurements. The different degrees of progress that have been made in the development and use of measurements to further our understanding of forage quality are described and related to their fitness of purpose. It is concluded that …

Forage Quality And The Environment, C. E. Lascano, A. Schmidt, R. Barahona

IGC Proceedings (1977-2023)

The influence of environmental factors on forage quality of temperate and tropical grasses has been reviewed by several authors, who summarized how light, temperature, drought and soil nutrients influence chemical composition, and digestibility of forages grown in contrasting areas of the world. The effects of season of the year on forage growth, grazing behavior and animal performance have also been the subject of numerous papers and reviews. However, there are few recent reviews that summarize how changes in climatic and edaphic factors influence forage quality of legumes with variable levels of condensed tannins (CT), which are important secondary compounds in …

The Effect Of Perennial Ryegrass Cultivar Lock Up Length And Nitrogen On Forage Quality For Silage, Joseph L. Jacobs, Frank R. Mckenzie, G. N. Ward

IGC Proceedings (1977-2023)

A study was undertaken to determine the effects of three perennial ryegrass (Lolium perenne L.) cultivars (Vedette, Impact and Nevis) with differing maturities, lock up length and nitrogen (N) application upon the dry matter (DM) yield and nutritive characteristics of pasture for silage. The addition of N at 50 kgN/ha significantly (P< 0.05) increased DM yield for all cultivars. Metabolisable energy (ME) (MJ/kgDM) of the ryegrass declined with time for all treatments, although by week 8 of lock up the ME content of Vedette was significantly (P< 0.05) lower than for other cultivars. When the DM yield and ME content of ryegrass at early ear emergence for each cultivar was compared, the harvestable metabolisable energy (MJ/ha) was highest for Nevis followed by Impact and Vedette. In conclusion, there is potential to use later maturing cultivars of ryegrass in south east Australia to allow for later harvesting of forage for silage, whilst maintaining ME and maximising DM yields. Furthermore the use of N fertiliser can also increase DM yields without impinging on pasture quality.

Screening Fresh Forages For Protein Degradation And Nutritive Value, Garry C. Waghorn, J. L. Burke

IGC Proceedings (1977-2023)

A method has been developed to prepare fresh forages for in sacco and in vitro incubation by freezing and mincing to achieve a particle size distribution of dry matter (DM) similar to in vivo conditions. The method is described and data presented to indicate losses of nitrogen (N) during in sacco digestion and net yield of ammonia from proteolysis in vitro for 22 fresh and conserved forages. Grasses, legumes and herbs were evaluated, with fractional degradation rates of forages ranging from 0.07h^-1 with tall fescue (Festuca arundinacea) to 0.24 h^-1 with chicory (Cichorium intybus). …

Evaluation Of Ten Tropical Grasses In The Northwest Region Of The State Of São Paulo-Brazil, C. V. Soares Filho, L. R. De A. Rodrigues

IGC Proceedings (1977-2023)

The experiment was carried out in the northwest region of the State of São Paulo-Brazil to evaluate ten grasses recently introduced in the region. The grasses studied were: Cynodon nlemfuensis cv. Tifton 68, C. dactylon cv. Tifton 78, Cynodon spp. cv. Tifton 85, C. dactylon cv. Florakirk, C. nlemfuensis cv. Florico, C. nlemfuensis cv. Florona, C. dactylon cv. Coastcross, Paspalum notatum cv. Tifton 9, Brachiaria brizantha cv. Marandu, Panicum maximum cv. Tanzânia 1. The following variables were determined: DM production, growth rate, IVDMD, CP, ADF and NDF.

The GRs varied from 81 to 102 and from 14 to 26 Kg …

Evaluation Of Centrosema Rotundifolium For Sand-Soil Savannas In Eastern Venezuela, I. Rodríguez, R. Schultze-Kraft, S. González

IGC Proceedings (1977-2023)

An evaluation of a collection of amphicarpic Centrosema rotundifolium showed considerable variability among the six accessions tested, regarding above- and below-ground seed production. Dry-season forage yields were very low but rainy-season yields reached acceptable levels. Contents of crude protein, P and Ca were intermediate to high (CP and P) or low (Ca). Three accessions are suggested for on-farm testing in association with grasses in order to explore the plant persistence implications of belowground seed production under practical conditions. Furthermore, the potential of this amphicarpic species for the conservation of sandy soils deserves attention.