the effect of nitrogen rate on nitrogen use efficiency index in wheat (triticum aestivum l.) cultivars

in order to investigate the effects of different levels of nitrogen rate on yield and seed yield components of wheat cultivars, an experiment was conducted on araghi mahalleh (gorogan) research farm in 2008. treatments, nitrogen in the form of urea (0, 90, 180 and 270 kg/ha) and cultivars (tajan, falat and n81-18) were arranged as factorial based on randomized complete block design with four replications. measured parameter include: nitrogen use efficiency, nitrogen uptake efficiency, nitrogen utilization efficiency, nitrogen efficiency indices, protein seed. the best nitrogen indices were observed in control condition. also n81-18 cultivar had the highest nitrogen use efficiency, nitrogen utilization efficiency, nitrogen harvest index and the lowest nitrogen uptake efficiency. it has been shown that two multiple components of nitrogen use efficiency (nitrogen utilization efficiency and nitrogen uptake efficiency) had not similar contribution on nitrogen use efficiency and differences in nue seem to have been mostly associated with ute and less with upe for all cultivars.