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 1.28and 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.