Journal of Crop Production and Processing

In order to investige the effect of nitrogen and Azospirillum biological fertilizers on the growth and yield of an Iranian bread wheat (Roshan cultivar) this study was carried out using a factorial experiment based on a randomized complete block design with three replications at a field in Jozan region, Isfahan, Iran in 2013. The experimental factors included Azospirillum brasilense bacterium at two levels (inoculated or non-inoculated), and nitrogen fertilizer at five levels (0, 50, 100, 150 and 200 kg ha^-1 of N). The application of Azospirillum increased grain yield and agronomic characteristics including the number of spikes m^-2, 100-seed weight, protein content and SPAD number. The interaction effects of the two factors were also significant on grain yield, number of spikes m^-2, 100-seed weight and grain protein content (P≤0.05) and plant height and SPAD number (P≤0.01). The greatest grain yield (4607 kg ha^-1), grain protein content (12.71%) and SPAD number (53.33) obtained from the plants treated with Azospirillum and N-fertilizer at 50 kg ha^-1. The highest number of spikes per m² (471.42) and 100-seed weight (48.4 g) were produced by Azospirillum inoculation and N-fertilizer at the rate of 100 kg ha^-1. Overall, the inoculation with Azospirillum bacteria and the application of 50 kg ha^-1 N seemed suitable to achieve maximum grain yield, to reduce the adverse environmental impacts and to maintain the N-fertilizer. Albeit, further recommendation warrants future studies.