PHOSPHORUS EFFICIENCY IN PASTURE SPECIES .5. A COMPARISON OF WHITE CLOVER ACCESSIONS

Seed collections of 'naturalized' white clover (Trifolium repens L.) accessions, believed to have been derived from a Dutch 'wild white' clover introduced into the Northern Tablelands area of New South Wales were made. The collections were made from areas with low, high, and intermediate concentrations of extractable soil phosphorus. In a controlled environment pot experiment, the shoot and root growth and P uptake of each of these accessions was compared over a range of six P rates to three commercially available accessions-Ladino, Grasslands Huia, and Haifa and an accession from Algeria. Various methods of determining the efficiency of ultilization of P were examined. By all methods studied, Ladino generally was more efficient at utilizing applied P. Ladino produced a larger shoot biomass and greater length of root than other accessions, had a higher P uptake, and was more efficient in utilizing this P for the synthesis of biomass. The rankings of the clover accessions in terms of P efficiency changed according to the definition used. The study suggests that some scope exists for selection for P efficiency in clover accessions.