EVALUATION OF CLOVERS IN DRY HILL COUNTRY .4. COMPONENTS OF SUBTERRANEAN CLOVER REGENERATION AT WHATAWHATA, NEW-ZEALAND

The components of regeneration of nine subterranean clover (Trifolium subterraneum L.) cultivars were measured for 3 years on steep, intertrack areas located on a north-west-facing hillside. During the period of flowering and seeding, two grazing managements were compared, viz: on-off sheep grazing (RG) or continuous sheep grazing (CG). Annual rainfall was 1200-1500 mm, but during December-April regular wetting/drying cycles were experienced. High levels of reseeding occurred across the range of maturity types, viz: 'Seaton Park' to 'Tallarook'. More important than maturity date in determining reseeding was the compatibility of growth habit with intensive grazing management. Prostrate cultivars ('Tallarook', 'Mt Barker', 'Howard') reseeded more profusely and regenerated more successfully. Cycles of seed germination/seedling death were common during January-April. Propensity to germination in summer-early autumn was greatest in 'Nangeela' and 'Woogenellup'. Seedling survival during autumn had a major impact on annual variation in subterranean clover density, but within each year plant number was also influenced by competition from other pasture species. Seed inputs of 2000/m2 were sufficient to generate maximum subterranean clover densities within the pasture community of this hill environment.