Intraspecific Variation in Nitrogen Uptake and Nitrogen Utilization Efficiency in Wheat (Triticum aestivum L.)

Twenty wheat ( Triticum aestivum L.) varieties differing in plant height were grown in soil culture and evaluated for differences in nitrogen uptake and nitrogen utilization efficiency (NUE) at limited (40 kg N ha⁻¹) and normal (120 kg N ha⁻¹) nitrogen supply. Nitrogen uptake showed 1.4- and 1.5-fold varietal variation at harvest for limited and normal N supply, respectively. NUE for dry matter production (NE1) exhibited 1.28- and 1.38-fold genotypic variation while NUE for grain production (NE2) varied by 1.25- and 1.21-fold at limited and normal N supply, respectively. Tall varieties were found to have higher N uptake and NUE for dry matter production, while dwarf cultivars had greater NUE for grain production. Nitrogen uptake was found to be strongly positively associated with dry matter production (r=0.85 and r =0.77 at limited and normal N supply, respectively), indicating an important effect of growth rate on N uptake. NUE for biomass production, as well as for grain production, was reduced as the supply of nitrogen was increased.