Competition between Clare and Seaton Park, and Clare and Daliak subterranean clovers in replacement series mixtures in the field.

Abstract

Binary mixtures of Clare and Seaton Park, and Clare and Daliak subterranean clovers were grown for three years in de Wit replacement series in the field and defoliated at approximately 4-week intervals between mid-winter and the end of October. For the most part both mixtures exhibited competition for the same resources with Clare dominant, and progressively excluding the other cultivars; this exclusion was more rapid with Daliak than with Seaton Park. Seed production of both Seaton Park and Daliak was depressed in mixtures, and seed reserves were reduced to virtually zero by the third year, although significant growth and seed reserves remained in the monocultures. Seed production from Clare was much less dependent on plant population than was seed production from Seaton Park and Daliak. Variation between replicates and spatial heterogeneity of sward composition was greater in the Daliak experiment on a heavy clay than in the Seaton Park experiment on a lighter soil. In both experiments, large quantities of seed could not be accounted for in germinations and residual seed reserves-80% in 1986 and 33% in 1987. Significant seed losses may be characteristic of the ecology of subterranean clover in summer rainfall zones. The success of Clare in northern New South Wales may be due mainly to the vigour and high seed production capacity of individual plants.