Effects of defoliation frequency and nitrogen and phosphorus nutrition on performance of 4 white clover cultivars

摘要

Abstract White clover plants, defoliated either 3-or 6-weekly, were grown in potted soil with a range of phosphorus and nitrogen additions. Four cultivars (‘Grasslands Huia’, ‘Grasslands Pitau’, S100, and Blanca RVP), were used as examples to investigate the effect of defoliation frequency on expression of genetic variation for response to P and N treatments. Defoliation 3-weekly favoured the detection of genetic variation in DM yield response to P treatment whereas the converse was true for response to N treatment. The P main effects and interactions were linear in form, but the cultivar × N interaction was bimodal. Reasons for these contrasting responses are discussed and the importance of careful definition of defoliation frequency when screening white clover is stressed.