N allocation into wheat grains (Triticum aestivum L.) influenced by sowing rate and water supply at flowering under a Mediterranean climate.

This study examined the effects of a reduced wheat sowing rate (250 vs. 500 grains m) on grain yield, uptake of N into grains, and the incorporation into gluten and non-gluten proteins of wheat under field conditions in the Aegean region. A single N application was applied at stem elongation, at flowering, or at both developmental stages. Each N treatment included either additional water supply, or no additional water supply at flowering. Sowing rate (either 250 or 500 grains m) had no impact on grain yield. Grain yield increased with additional water supply, but at the expense of protein quality, because of a decrease in the protein content of gluten. The N content of the gluten and non-gluten proteins at grain maturity was not different among cultivars. N applied at both stem elongation and flowering was found in comparable amounts in grains and protein fractions, irrespective of sowing rate.