Evaluation of some annual Trifolium spp. under irrigation

Abstract

Eighteen annual species (38 lines) of the genus Trifolium were sown in 1982 as nursery plots to evaluate their potential under irrigation at Kyabram in northern Victoria. A wide range in plant habit, plant growth and flowering time was observed both within and between species. This experiment was used to select species for further agronomic evaluation; those selected were T. balansae CPI45856, T. purpureum cv. Paratta, T. resupinatum cv. Maral and the subterranean clover species T. brachycalycinum cv. Clare, T. subterraneum cv. Woogenellup and T. yanninicum cv. Trikkala. Pure swards of T. balansae, T. resupinatum and a mixture of subterranean clover cultivars were sown on five occasions in 1983. The first four sowings were established by irrigation on 7 February, 28 February, 21 March and 11 April; the fifth was sown on 20 June. T. purpureum was included only on 28 February and 20 June. Establishment was low (35% of germinable seed sown) at the first two times of establishment, when temperatures and evaporation rates were high. Early establishment increased the productivity of all species, by increasing autumn-winter production with only slight indications of a decline in spring growth. Spring productivity of T. resupinatum was superior to all other species. Irrigation into early summer maintained the growth of T. resupinatum but not of the other species. Data on growth rates, in vitro dry matter digestibility and nitrogen content are also presented.