This study examined the effects of a reduced wheat sowing rate (250 vs. 500 grains m-2) on grain yield, uptake of 15N into grains, and the incorporation into gluten and non-gluten proteins of wheat under field conditions in the Aegean region. A single 15N application was applied at stem elongation, at flowering, or at both developmental stages. Each 15N treatment included either additional water supply, or no additional water supply at flowering. Sowing rate (either 250 or 500 grains m-2) 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 15N content of the gluten and non-gluten proteins at grain maturity was not different among cultivars. 15N applied at both stem elongation and flowering was found in comparable amounts in grains and protein fractions, irrespective of sowing rate.
Keywords: Gluten; Turkey; grain yield; irrigation; isotope biology; isotope ecology; nitrogen-15; proteins; sowing rate; wheat.