Response of burr burial in subterranean clover (Trifolium subterraneum) to defoliation

Abstract

Four defoliation treatments before flowering were imposed on twelve genotypes from three subspecies of Trifolium subterraneum. The experiment was conducted on a sandy soil with irrigation supplementing the natural rainfall. The severest defoliation doubled the percentage and tripled the absolute yield of buried seed. Highly significant differences were found between the genotypes within subspecies, indicating that selection for subterranean clover pastures with a range of ability to bury burrs is possible. No differences in genotype or subspecies response to defoliation nor differences of absolute seed yields were obtained. It is suggested that sward density is very important when experiments evaluating subterranean clover genotypes include defoliation treatments of the swards.