BREEDING AND EVALUATION OF NEW WHITE CLOVER VARIETIES FOR PERSISTENCYAND HIGHER YIELDS UNDER GRAZING

Two experiments were established in 1989 and 1990 to evaluate the perf ormance of white clover (Trifolium repens) varieties under grazing, us ing sheep and cattle, and also under a 'cutting-only' regime. The thre e potential medium/large-leaved varieties (AberVantage, AberCrown and AberDai) were selected and evaluated in a breeding programme that emph asized improving yield and persistency under grazing. In Experiment 1, the potential varieties were sown with two different grass companions , and evaluated under a continuous cattle-grazing system, representati ve of their future role in actual farm practice, i.e. a set stocking s ystem. Clover yield of the potential varieties in the second harvest y ear averaged 1.5 t ha(-1) more than the control variety Olwen. Total s ward production of AberVantage, AberCrown and AberDai was 2.0-1.4 t ha (-1) higher than that of Olwen. In Experiment 2, clover yields of the three potential varieties averaged 2.1 t more than Olwen in the second harvest year under continuous sheep grazing, but all three were lower yielding than Olwen in the cutting regime. Both experiments illustrat e how the use of grazing treatments during breeding and evaluation can improve the role of white clover varieties.