The phosphorus content and yield of grain of different wheat varieties in relation to phosphorus deficiency

Abstract

Several varieties of Australian and two American bread wheats were grown in the glass-house under conditions of controlled phosphorus deficiency. A wide range of final phosphorus concentrations occurred in the grain of all varieties in response to variations in phosphorus supply. Suffcient phosphorus at sowing raised the value for Australian grain to 0.4% P. Under deficiency conditions, the concentration in all varieties fell below 0.25% P, a typical value for grain from southern Australia. Yields of two Australian varieties, Bencubbin and Charter, were further examined. Variety Bencubbin was shown to give larger grain yields than Charter under conditions of phosphorus deficiency, and its grain had lower concentrations of phosphorus. The higher yields were not associated with higher uptakes of phosphorus. Bencubbin showed a marked luxury uptake in the straw at moderate rates of phosphorus application. It is suggested that the lower phosphorus concentrations in the higher-yielding variety are necessarily associated with success in selection for dry matter yield, where the uptake of the nutrient is limited.