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 re...