Effect of nitrogen fertilization and post-maturity rainfall on wheat grain quality

Abstract

Effects of nitrogen (N) fertilizer and weather condition on wheat quality (protein content in grain, and viscosity and brightness of the flour) were studied. Supplying 160 kg N/ha (160N) to winter wheat increased the protein content when compared to those plants supplied 40N, 80N or 120N. Brightness (L*) of the flour was lower in the treatment with 160N. The viscosity was less affected by nitrogen supply than the protein content. Germination rates of wheat grains harvested at late growth stage were high because rainfall after grain maturity resulted in pre-harvest sprouting of grain. Viscosity and brightness in the treatment with 120N and 160N were low. In grain samples collected from 43 fields in Hokkaido Prefecture, negative correlations were observed between protein content and brightness. Brightness decreased rapidly when the protein content became to more than 110 mg/g grain. Germination rate correlated negatively with the viscosity and brightness of the flour.