L.A. EDYE¹, T.J. HALL², R.L. CLEM³, T.W.G. GRAHAM⁴, W.B. MESSER¹, and R.H. REBGETZ¹

¹CSIRO Tropical Agriculture, Townsville
²QDPI, Roma Research Station, Roma, and
³Brian Pastures Research Station, Gayndah, and
⁴Rockhampton, Queensland, Australia

Abstract

Sown pasture development in the light-textured soils of the seasonally dry tropics and subtropics is based mainly on Stylosanthes species. S. scabra cv. Seca, the cultivar most widely sown, has poor long-term persistence and yield in lower-rainfall subtropical environments experiencing frosts and drought, particularly on clay soils. This study has identified accessions of "Stylosanthes seabrana" which perform well on clay soils in the subtropics, greatly extending the contribution that Stylosanthes species can make to beef production in northern Australia.
Although there was abnormally low rainfall during the first 2 years of the experiment, the stylos established and survived in all environments. Most "Stylosanthes seabrana" accessions were consistently superior to Seca in seedling and perennial plant density and yield at most sites, particularly in the third year of the experiment. Seca performed poorly in all attributes in all years with the lowest rank over all years indicating its lack of adaptation.
The accessions 92838B and 110361 were selected and released as cultivars Primar and Unica, respectively, in 1996. Primar appears better adapted to the more southerly subtropical sites with early frosts and a short growing season. Unica appears superior to Primar in central Queensland which normally has a longer summer growing season.