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. Results showed that N81-18 cultivar with nitrogen rate of 180 Kg/ha had highest yield) 5959.8 Kg/ha) and Falat cultivar with nitrogen rate of 0 Kg/ha had lowest yield) 3129.33 Kg/ha). All cultivar in some properties such as number of fertile tillering, seed yield, biological rate, harvest index showed an increase for nitrogen rate of 90, 180, 270 Kg/ha with respect to the nitrogen rate of 0 Kg/ha and N81-18 cultivar because of the higher fertile tillering, biological yield, seed yield and harvest index in all of nitrogen levels showed and advantage with respect to other cultivars.
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