Agronomy and Crop Sciences Commons^™

'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.

Metabolic Engineering Of Peanut Hairy Roots Via Rna Interference To Study The Role Of Prenylated Stilbenoids Against Water Stress, Gaurav Gajurel

Student Theses and Dissertations

Abiotic stress, such as drought, causes over five-hundred million dollars in losses in peanut production per year in the world. Peanuts are known to produce antioxidant prenylated stilbenoids, however, their role in abiotic stress tolerance have not been elucidated. The overall goal of this project was to determine if selected prenylated stilbenoids play a role against water stress in peanut. To address this issue, transgenic hairy roots with the capacity to produce diverse prenylated stilbenoids using an RNA-interference (RNAi) approach were established. RNAi molecular constructs targeting a stilbenoid-specific prenyltransferase were designed, synthesized, and expressed via Agrobacterium rhizogenes-mediated transformation in peanut …

Genome-Wide Dna Polymorphism Analysis And Molecular Marker Development For The Setaria Italica Variety “Ssr41” And Positional Cloning Of The Setaria White Leaf Sheath Gene Siwls1, Hui Zhang, Sha Tang, James C. Schnable, Qiang He, Yuanzhu Gao, Mingzhao Luo, Guanqing Jia, Baili Feng, Hui Zhi, Xianmin Diao

Department of Agronomy and Horticulture: Faculty Publications

Genome-wide DNA polymorphism analysis and molecular marker development are important for forward genetics research and DNA marker-assisted breeding. As an ideal model system for Panicoideae grasses and an important minor crop in East Asia, foxtail millet (Setaria italica) has a high-quality reference genome as well as large mutant libraries based on the “Yugu1” variety. However, there is still a lack of genetic and mutation mapping tools available for forward genetics research on S. italica. Here, we screened another S. italica genotype, “SSR41”, which is morphologically similar to, and readily cross-pollinates with, “Yugu1”. High-throughput resequencing of “SSR41” …

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 …

A Chickpea Genetic Variation Map Based On The Sequencing Of 3,366 Genomes, Rajeev K. Varshney, Manish Roorkiwal, Shuai Sun, Prasad Bajaj, Annapurna Chitikineni, Mahendar Thudi, Narendra P. Singh, Xiao Du, Hari D. Upadhyaya, Diego Jarquin

Department of Agronomy and Horticulture: Faculty Publications

Zero hunger and good health could be realized by 2030 through effective conservation, characterization and utilization of germplasm resources1 . So far, few chickpea (Cicerarietinum) germplasm accessions have been characterized at the genome sequence level2 . Here we present a detailed map of variation in 3,171 cultivated and 195 wild accessions to provide publicly available resources for chickpea genomics research and breeding. We constructed a chickpea pan-genome to describe genomic diversity across cultivated chickpea and its wild progenitor accessions. A divergence tree using genes present in around 80% of individuals in one species allowed us to estimate the divergence of …

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.

Methodology To Evaluate Forage Legumes For Oversowing Grasslands In The Basaltic Region Of Uruguay, D. Real, J. Franco, J. Crossa

IGC Proceedings (1977-2023)

A methodology used to evaluate around 300 temperate and subtropical forage legumes for oversowing the native grasslands of the Basaltic Region of Uruguay is presented in a four-year plan using the minimum amount of seeds per accession and resources. Row-column experimental designs are used to reduce the error variance existing due to the large soil heterogeneity intrinsic to the Region. The ability of the species to grow and reproduce was measured and adjusted least square means were estimated to rank them. Cluster analysis was also useful to group species with similar behaviour overall traits. Preliminary results for the temperate species …

Seasonal Variation Of White Clover Morphology At The North Of Buenos Aires Province, Argentine, E. M. Pagano, Jorge O. Scheneiter

IGC Proceedings (1977-2023)

In order to study the seasonal variation in morphological characters that contribute to forage production in white clover (Trifolium repens L.) cultivars, a trial was conducted at Pergamino Agricultural Experimental Station INTA located north of Buenos Aires province, Argentina. The experimental plots were set out in a completely randomized design with four replicates. Measurements were performed over eight seasons throughout two years. The used cultivars had been previously reported as having differences in seasonal productivity. Significant differences were detected among seasons for all measured characters i.e. stolon length, number of buds, branches and leaves, and leaf area. Differences among …

Stolon Attributes Related To Persistence Of White Clover In Buenos Aires, Argentina, E. M. Pagano, Jorge O. Scheneiter

IGC Proceedings (1977-2023)

A trial was carried out at Pergamino Agricultural Experimental Station (33º 56’ S, 60º 33’ W), Argentina, to study the stolon morphology of white clover cultivars with different leaf size, inflorescence production through reproductive cycle, and vegetative persistence. Treatments were four white clover cultivars: Espanso (Italy), Experimental L.49 (Argentina), Jacui S2 (Brazil) and Nora (Sweden). A completely randomized block design was used (n=6). Throughout two years, measurements of stolon length and dry and organic matter were performed every 60 days. The inflorescence number was also recorded. Results showed significant differences among cultivars in all the studied characters and almost in …