Phosphorus use efficiency in wheat and barley

Abstract

Genetic variation in responsiveness to P under field conditions was examined in up to 48 varieties of wheat or barley grown with 0 or 30 kg P/ha at Mallala and Halidon (SA) (sites with low available soil P). Early biomass production was assessed non-destructively using NDVI and significant responses to P and differences among the genotypes occurred but there was no significant Variety x P interaction. Grain yield responses to P were 5-10% at Mallala and 40-50% at Halidon. Neither grain yield nor the yield responses to P were associated with the P responses observed in NDVI. Yield at low P, one measure of PUE, showed strong genetic correlations between sites and with yield with P fertiliser. Genetic correlations for responsiveness to P across sites were much smaller. The ability to respond to P fertiliser and the yield under low P supply did not show strong genetic correlations suggesting that it may be possible to select for the two traits independently. Although there was a strong influence of site on P responsiveness, some genotypes of wheat and barley showed consistent efficiency across sites, and selection based on yield at low P supply as well as the ability to respond to P should be feasible.