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A collection of naturalized annual pasture legumes in the semi-arid cereal-livestock zone of south Australia

M.T. Spencer, G.C. Sweeney, W.D. Bellotti and G.C. Auricht

SARDI. Turretfield Research Centre, Rosedale SA 5350
SARDI, Northfield Research Laboratories, GPO Box 1671, Adelaide SA 5001

Historically, naturalized ecotypes of annual pasture legumes have been sources of well-adapted commercial cultivars. In many instances, these accidentally introduced ecotypes have had in excess of fifty generations to evolve and adapt to local conditions. To utilise these local genetic resources for pasture improvement programmes. naturalized annual pasture legumes were collected on hard-setting red-brown earths in the semi-arid uplands of the cereal-livestock zone of SA.


Fifty three collection sites were selected on and around the transition between the southern Flinders Ranges and the Northern Mount Lofty Ranges. Annual rainfall declines from 400 to 250 mm from the southern to the northern boundaries of the collection zone. Altitude varies between 275 to 789m above sea level. The topography consists of north-south ridges with montane plains. This causes rainfall. temperature and soil type to vary considerably over short distances. The collection targeted specific niches rather than a systematic sampling and so does not define the overall distributions of local species.


Fourteen species from four genera were collected. Trifolium and Medicago were the most common genera. Lotus and Vicia were found at only one site each. Accessions of M. minima and M. truncatula were the most numerous species (Table 1). Medics were found over a wider range of pH than the clovers. 67% of Trifolium accessions and 41% of Medicago accessions occurred in the pH range 6.0-6.5. (69% of all sites). Of these, most species were found on clay loams and sandy clay loams which were the dominant textural classes of the eight soil textural classes encountered. Both genera were distributed across a broad range of rainfall and altitude but the aerial seeding T. angustifolium, T. arvense, T. campestre, T. glomeratum and T. tomentosum, tended to occur at wetter, higher sites. This trend was also apparent with the smaller seeded medics, M. minima and M. praecox.

Table I. Environmental characteristics of the collection sites of the most numerous species.

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