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Identifying persistent lucernes for the pastoral zone

Williams, R.W. Dr; Ph: (02) 6763 1205; Fax: (02) 6763 1222; rex.williams@agric.nsw.gov.au

Research organisation: NSW Agriculture, Yanco Agricultural Institute, PMB, Yanco NSW 2703

Collaborators: Data from the South Australian Department of Agriculture were used in this project as part of the National Lucerne Improvement Program.

Sponsors: AWRAPO: Australian Wool Research and Promotion Organisation

Objectives:

  • to identify plant traits associated with the persistence of lucerne in rainfed pastures.;
  • to assemble several elite populations which possess these desirable traits;
  • to aid the development of a definitive lucerne cultivar for rainfed pastures and ultimately improve the productivity of the pastoral zone.

Methodology:

Plant traits potentially involved in lucerne persistence were measured in field, greenhouse and controlled-environment experiments. These experiments investigated aspects of carbohydrate partitioning, winter-activity, response to water deficit, the morphology of crowns, roots, and stems, and pest and disease resistance. These data were combined with persistence data from existing field trials and particular traits, or combinations of traits, associated with differences in the persistence of lines identified using multivariate analyses. These results will help improve the breeding of adapted lucernes specifically for rainfed pastures.

Progress:

Although varieties differed in morphological and physiological traits, no single trait reliably predicted variation in plant persistence within rainfed trials at Yanco and Tamworth. However, persistence at both sites could be explained by multiple regressions which combined differences in the mean lengths of the longest stems during summer after 33 days regrowth and those during winter after 46 days regrowth. Persistent lucernes had relatively long stems in summer but relatively short stems in winter. The water use efficiencies, carbohydrate utilisation patterns, and resistances to pests and diseases of the different lucernes provided only minor or negligible improvements to this simple stem-length model. However, varieties with long stems in winter also had generally lower water use efficiencies and were more exploitive of root carbohydrate reserves during regrowth than varieties with shorter stems in winter. Limited data also suggested that the most water-use efficient varieties were the same irrespective of water availability. An average pattern of carbohydrate utilisation after herbage removal was described and this was associated with ideal grazing or cutting intervals. Data from these trials also supported the release of 'Genesis' as a persistent lucerne for high production in rainfed pastures.

Period: starting date 1991-07; completion date 1994-06

Status: completed

Keywords: lucerne persistence, lucerne selection, drought tolerance

Publications:

Williams, R.W. (1995). Breeding better lucernes for crop rotations. In Proceedings of the Victorian Cropping Conference, edited by K. McCormick and B. Williams, Longerenong College, Melbourne, Vic., pp. 131-132.

Williams, R.W. and Boschma, S.P. (1996). Identifying persistent lucernes for dryland pastures. In Proceedings of the Eighth Australian Agronomy Conference, Toowoomba, edited by M. Asghar, ASA Inc., Parkville Vic., pp. 586-589.

Williams, R.W. and Young, R.R. (1996). Register of Australian Herbage Plant Cultivars: Medicago sativa L. (lucerne) cv. Genesis. Australian Journal of Experimental Agriculture 36, 521-522.

 

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