L.B. HACKER

Division of Tropical Crops and Pastures, CSIRO, Brisbane, Queensland, Australia

Abstract

Setaria sphacelata (setaria) is a widely sown pasture grass in wetter regions of the sub-tropics and tropics of Australia and elsewhere. The species is extremely variable, and it was considered that there were opportunities for improving yield in the cool season, winter greenness, digestibility and seed production by breeding. Sward trials are described in which 13 populations of setaria were grown with nitrogen fertiliser or with a legume at two sites. in southeast Queensland, for three years. The setarias included nine advanced breeding populations. one accession and the cultivars Nandi, Narok and Kazungula. Plots were harvested at c. 6-weekly intervals. Dry matter yield and inflorescence numbers were recorded, as well as winter-greenness following frosting. For several harvests, in vitro digestibility and percentage stem were also measured.
Yields from N-fertilised swards differed significantly for all but three of the 12 site-season (2 sites, 3 years, winter and summer) combinations. At Lawes, Narok was consistently higher yielding than other setaria cultivars, especially in winter. At Beerwah, Narok was markedly superior to Kazungula in winter but otherwise differed little from other entries. None of the breeding populations was significantly higher yielding than Narok.
Total yield from legume-based swards differed for only three of the six sites-years and legume yield only once. The setarias showed large differences in flowering and winter-greenness and significant differences in digestibility.
It is concluded that the bred populations of setaria studied showed little advantage over Narok under the management systems imposed, but that phenological differences could be associated with improved seed production as compared with Narok, which is commercially regarded as a poor seed-producer. Two of the breeding populations were later combined and released as the cultivar Splenda and another as cv. Solander.