COMPARISON OF THE PERFORMANCE OF SUBTERRANEAN CLOVER CULTIVARS IN SOUTHERN NEW-SOUTH-WALES .1. PERSISTENCE, PRODUCTIVITY, AND SEED YIELDS

The density, productivity, flowering characteristics, and seed reserves of 14 lines (10 cultivars and 4 experimental lines) of subterranean clover were observed over 5 years (1983-87) on a red earth soil at Wagga Wagga, New South Wales. Plant density increased from 149-318 plants/m2:in 1983 to 1975-13925 plants/m2 in 1987. Herbage yields of all cultivars during autumn-winter were similar in most years except in July 1985 when Seaton Park was superior. Cultivars in the midseason or later flowering groups were more productive in late spring and better able to utilise the extended growing seasons that occur periodically in this environment. The mean time from emergence to 5% flowering of all cultivars was 168 days with March germination in 1985 but decreased to 135 days with May germination in 1986. The number of days to flowering at Wagga Wagga was highly correlated with maturity ranking at Perth (r2 = 0.92 in 1985 and r2 = 0.93 in 1986). In the first year, average seed set was 295 kg seed/ha, but by summer of the fourth year the seed pool ranged from 124 kg/ha for Clare to 1190 kg/ha for Nungarin, the earliest flowering cultivar. The quantity of hard seed that carried over to the next year varied significantly between cultivars, with Enfield, Woogenellup, and Clare having the least, and Nungarin, Northam, Dalkeith, and Daliak the most. Seed set was related to maturity ranking only in 1984, although root disease probably affected seed yields in 1985-86. The proportion of hard seed that carried over was much higher than expected, particularly in soft-seeded cultivars. The newly released cultivar Junee was well adapted to the environment; it was later maturing than the recommended cultivar Seaton Park but was able to maintain high seed reserves. Karridale, another new cultivar, maintained higher seed reserves than the older Mount Barker.