Performance of white clover cultivars and breeding lines in rotationally grazed Waikato dairy pasture, New Zealand

The performance of 30 white clover breeding lines, including some already r eleased cultivars, was measured over four years (I June 1993 to 31 May 1997 ) in mixed pasture under rotational grazing by dairy cows, in the Waikato r egion of New Zealand. All the white clovers persisted throughout the trial but parameters measured (visual scoring of vigour, clover yield, and clover %) showed that the performance of most lines and cultivars fell in the fin al season due mainly to cooler than normal growing conditions in late winte r-summer and a dry spring-summer. 'Grasslands Pitau' was, overall, the top white clover cultivar but showed a significant drop in performance during t he dry 1996/97 year. Six other lines, including a newly released cultivar, 'Kopu II', were in the group of top performing white clovers characterised by high visual scores, clover yields, and clover % in the 1996/97 year. 'Gr asslands Kopu', the control cultivar, performed poorly, ranking 25th overal l. Results indicated that clover persistence is still a problem in dairy pa stures, particularly if the climate is dry. Overall, the trial showed that persistence and drought tolerance should be a major focus of future white c lover breeding programmes aimed at developing cultivars more suitable for d airy farming in New Zealand.