Effect of grazing intensity and cultivar on morphology, phenology, and nutritive value of subterranean clover. 1. Morphology and phenology of subterranean clover during the growing season

Abstract

The effect of grazing intensity and cultivar on plant morphology was examined with 26 cultivars of subterranean clover during the growing season. The cultivars were grown in 3 groups (early, mid, and late) according to their flowering time and grazed under 2 grazing intensities (heavy and light) at a 2-weekly interval.

Heavy grazing delayed flowering time by only about 2 days for early and late maturity cultivars without influencing flowering duration. Late and mid maturity cultivars had more (P< 0.05) branches, petioles, and leaves with shorter branches under heavy grazing than under light grazing, whereas early maturity cultivars did not show any significant differences in the numbers of plant parts under the 2 grazing intensities. The effect of grazing intensity on the proportions of plant parts was small over all cultivars, indicated by a 2 percentage unit increase in the proportions of leaf in September, burr in October, and stem in November by heavy grazing.

There was a large cultivar variation in flowering duration, and the numbers, lengths, and proportions of plant parts. The ranges of flowering duration were 24–66, 26–66, and 31–76 days and of branch length after cessation of flowering were 12–20, 6–14, and 5–14 cm for the early, mid, and late maturity groups, respectively. The late maturity group had more branches, leaves, petioles, and stems, and the early maturity group had less with the mid maturity group being intermediate. The variation in the proportions of plant parts among cultivars was not related to flowering time or flowering duration.