Seed production from three annual species of Trifolium on sandy soils in the wheat belt of Western Australia

Abstract

Seed production and persistence of subterranean, cupped, and rose clovers were examined over a period of three years in undefoliated swards, at several plant densities, in the wheat belt of Western Australia. Subterranean clover, although earlier flowering, was outyielded by the other two species in the two driest years. No major differences were found between species in relative water content of leaves during periods of soil moisture deficit. Moreover, species differences in soil moisture exploitation were small. A high proportion of inflorescences failed to set seed in subterranean clover. This reproductive defect, which is associated with restricted inflorescence burial due to dry soil conditions, was thought to be the main reason for the poorer seed yield in this species. Despite low seed yields in the establishment year, plant density after the first year did not seriously limit seed yields, even at the lowest seeding rate, in any of the three species.