Effects of plant density on seed yield in Caucasian clover (Trifolium ambiguum Bieb.) cv. Monaro

Abstract

A radial trial design was used to determine the effect of plant density on seed yield of Caucasian clover (Trifolium ambiguum Bieb.) cv. Monaro, and the seed yield response of twelve genotypes selected from within cv. Monaro. The five densities studied were 3, 6, 11, 20 and 28 plants per m⁻². Seed yield m⁻² was greatest at the 11 plants per m⁻² density, although differences from the 6 plants m⁻² density were not always significant. Inflorescence number per plant was the only seed yield component affected by plant density, numbers decreasing as plant density increased. The individual genotype seed yield response to increasing plant density was similar to that for the cultivar as a whole, except that some genotypes flowered only at low densities, while three remained vegetative irrespective of plant density. While poor plant growth meant that the seed yields recorded were low compared with other trial data for the same cultivar, the results do support the suggestion that for seed production, Caucasian clover should be sown at a rate of 2 kg ha⁻¹ and that sowing at higher rates will reduce inflorescence number and therefore seed yield.