Effects of Nitrogen and Azotobacter on Yield and Yield components of Wheat (Triticum aestivum L.) cv. Roushan

This research was carried out in a field factorial experiment based on randomized complete block design with three replications in a silty loam soil. Experimental factors were including two levels of Azotobacter chroococcum (seed inoculation with azotobacter at a concentration of 107 bacteria per gram and uninoculation) and five levels of nitrogen (0, 50, 100, 150 and 200 kg N.ha-1 from urea source). Azotobacter effect was significant on grain yield, number of grains per spike, grain protein content (P≤ 0.05), SPAD, number of spike per m2 and thousand grain weight (P≤ 0.01). Effect of nitrogen was significant on all of the traits except of number of grains per spike (P≤ 0.01). Interaction effect of two factors was significant on grain yield, SPAD (P≤ 0.05), plant hight, number of spike per m2 and number of grains per spike (P≤ 0.01). Grain yield was 4899 kg.ha-1 in combination of seed inoculation with azotobacter and nitrogen (100 kg.ha-1), which there was no significant differences with 150 and 200 kg N.ha-1. This fertilizer combination increased seed yield by 13.76%, compared to uninoculation and nitrogen (100 kg.ha-1). There were positive and significant correlation between grain yield and SPAD, number of spike per m2, number of grains per spike, thousand grains, plant hight and leaf area index (LAI). Overall, the inoculation with azotobacter bacteria and nitrogen (100 kg.ha-1) could achieve grain yield potential, reduce the adverse environmental impacts and save the N-fertilizer utilization