The influence of patterns of flowering of some subterranean clover (Trifolium subterraneum L.) accessions and cultivars on total seed set and autumn germination in a cool temperate environment with sporadic summer rain

Abstract

Fifteen accessions and 3 cultivars of subterranean clover (Trifolium subterranean L.) were sown in autumn in shallow stony soil south of Christchurch, New Zealand. The following growing season was atypical, with drought occurring briefly but one month earlier than usual, the rest of the season being wetter than usual. Contrary to previous results highest seed yields were given by mid- to late season flowering lines. Early flowering lines were severely disadvantaged by the early drought, resulting in seed yields of only 20-25 kg/ha. High seed yields were linked with the ability of lines to recommence flowering after drought and continue this for a prolonged period. Two late flowering accessions, 014454B and 014205B, yielded more than 200 kg/ha seed, outyielding the late flowering cv. Tallarook in spite of this cultivar having the same ability as the other two to reflower. Six highseed yielding lines gave naturally regenerated seedling numbers near to or exceeding 1000/m². Apparent hardseededness at the time of autumn germination averaged 49% which was lower than expected for this site. It is concluded that late flowering lines of subterranean clover should always be included in mixtures of this species for pasture to ensure adequate regeneration in wetter than normal seasons.