Effect of competition by white clover on the seed production characteristics of subterranean clover

Abstract

During the third year following establishment, the production, hard-seededness and dormancy of subterranean clover cv. Woogenellup when grown along and in association with white clover was studied in commercial pastures on the Northern Tablelands of New South Wales. The pasture containing only subterranean clover produced 757 mg seed dm-2, whereas in competition with white clover only 34 mg dm-2 was produced. A study was made of seed production by subterranean clover grown in competition with white clover. As the level of competition increased there was a marked decline in individual plant size, flowers per plant, seeds per burr and total seed production per plant, whereas no significant effects on seed dormancy and hard-seededness were apparent. A study of the seed and seedling population of the pure subterranean clover paddock revealed a recovery of 13% of the initial seed population as surviving plants and 32% as viable hard seeds at the beginning of winter. These observations suggest that competition from white clover could be a significant factor in some situations influencing the persistence of subterranean clover on the Northern Tablelands, and selection of cultivars with better ecological combining ability with white clover might be a worth-while objective.