Physiological Predetermination of the Order of Hardseededness Breakdown in Subterranean Clover (Trifolium subterraneum L.)

Abstract

Hardseededness breakdown in the burr of subterranean clover (Trifolium subterraneum L.) was found to be non-random in occurrence with respect to the relative position of seed in the burr. This suggests the presence of a predeterminative mechanism of the order of hardseededness breakdown. While seed moisture content did not exhibit a pattern of variation consistent with that for hardseededness breakdown, seed weight variation appeared to conform closely with the pattern of breakdown. It is postulated that, either differences in seed size per se within the burr may determine the order of hardseededness breakdown, or that such differences may reflect a disproportionate supply of translocate, and hence promotors or inhibitors, of hardseededness breakdown to the seeds of the burr. The implications of this finding to the assessment of genotypes for differences in level of hardseededness level have been outlined.