Agricultural Science Commons^™

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 …

Observation Of Root Rot And Internal Breakdown Of Redclover (Trifolium Pratense L.) In The 3rd Year, H. Nakashima, H. Morishita, T. Hirata, K. Yoshida

IGC Proceedings (1977-2023)

Two red clover (Trifolium pratense L.) cultivars; Hokuseki and Merviot were surveyed growth habits and deterioration at the crown and taproot in the 3rd year. Each cutting plants were marked and measured the plant height and dry matter weight. After 3rd cutting of the 3rd year, plants were digged out and scored the degree of root rot and internal break down (no symptom: 0-severe damaged: 5). The severe damaged plants at the 3rd cutting tend to have larger plant size at the 1st cutting. And other root development traits during growth were observed.

Amphicarpy In The Tropical Legume Centrosema Rotundifolium: A Research Project In Eastern Venezuela, S. Müller, R. Schultze-Kraft, I. Rodríguez

IGC Proceedings (1977-2023)

Amphicarpy is a particular reproduction mechanism by which a plant can produce both above-ground and below-ground seeds and thus has the potential to contribute to an enhanced persistence of a plant population. It can be found in a range of tropical legumes, e.g. in several Centrosema species. The balance between above- and below-ground seed production is evidently influenced by environment and management factors but these influences are not well known. In the case of perennial tropical legumes, in addition to seed production shifts the allocation of resources affects also the production of tuberous roots as storage organs. A research project …

Rooted Plantlet Production In A Vegetatively Reproductive Red Clover (Trifolium Pratense L.) Cv. Astred, M. G. Hyslop, Peter D. Kemp, J. Hodgson

IGC Proceedings (1977-2023)

Vegetatively reproductive cultivars of red clover (Trifolium pratense L.) can produce clonal daughter plantlets under certain management and environmental conditions, which may improve sward persistency. Six trials involving spaced plants, pure swards or grazed mixed swards were conducted near Massey University, Palmerston North, New Zealand, from 1995 to 1998. Rooted plantlets counted in autumn of each year ranged from 5.8±1.6 to 43±5.1 rooted plantlets/parent plant for ungrazed spaced plants, and 0 to 1.8 rooted plantlets/parent plant for pure and mixed swards under grazing management. It is concluded that clonal, rooted plantlet production is highly variable in Astred depending on …

Selecting Crimson Clover For Hard Seed And Late Maturity, G. W. Evers, G. R. Smith

IGC Proceedings (1977-2023)

Available crimson clover (Trifolium incarnatum L.) cultivars in the USA flower approximately 2 weeks before annual ryegrass (Lolium multiflorum L.) which makes it difficult to manage a mixture of the two for reseeding. The objective of this study is the development of a crimson clover cultivar that flowers at approximately the same time as annual ryegrass and has a high level of hard seed to enhance reseeding. Selections for late maturity were made out of >Chief= crimson clover. After two cycles of selection for later maturity and one cycle for hard seed, nineteen half-sib lines were identified that …

A Novel Technique To Produce Polygenic Resistance To Anthracnose In Stylosanthes Capitata, Bela Grof, Celso D. Fernandes, A. T. F. Fernandes

IGC Proceedings (1977-2023)

An improved cultivar, based on 17 genotypes of S. capitata and six of S.macrocephala, was developed at the Embrapa Beef Cattle Research Center, Campo Grande, Brazil. The aim was to create durable, race non-specific resistance to anthracnose controlled by polygenic factors. A mass hybridisation technique was employed to produce a high degree of genetic diversity and sizeable quantities of seed of hybrid-derived progenies of Brazilian and Venezuelan genotypes of S. capitata. Outcrossing resulted in a significant improvement in the forage production of progeny of Venezuelan accessions. The multicross was evaluated in multilocational trials, each representing a large tract …

Genetic Resources For Tropical Areas: Achievements And Perspectives, Cacilda B. Do Valle

IGC Proceedings (1977-2023)

This paper analyses the present status of tropical forage resources and their utilization in the development of novel cultivars based on the accumulated information from past decades of collecting, evaluation and whatever little breeding has been pursued. The situation of world collections of tropical forages is presented and discussed in the light of limited investment and dwindling resources. A cause for concern is the lesser priority assigned to conservation and manipulation of official tropical germplasm banks, such as CSIRO’S and CIAT’s. In order to assure the availability of tropical genetic resources for the future it is imperative that international efforts …

Genetic Resources For Temperate Areas - Achievements And Perspectives, Mónica Rebuffo, T. Abadie

IGC Proceedings (1977-2023)

The processes of natural evolution and domestication of temperate forage genetic resources resulted in a build-up of genetic diversity, being remarkable in natural populations of grasses and legumes from Central Europe and the Mediterranean basin. Worldwide utilization of few species caused further increment in intraspecific genetic differentiation, meanwhile landraces became adapted to local agricultural production systems. Highlights are given to the risk of genetic erosion of indigenous grasslands as a consequence of the ecosystem modifications imposed by agriculture, as well as the drastic reduction of intraspecific genetic diversity caused by the process of plant breeding and environmental leveling in modern …