Effect of seed inoculation with Azotobacter and Azospirillum and different nitrogen levels on yield and yield components of canola (Brassica napus L.)

In order to investigate the effect of different levels of nitrogen and bio-fertilizers on yield of canola plants in Qazvin, Iran, a split-plot design was conducted on the base of randomized complete block design with four replications. Treatments included 3 levels of nitrogen (0, 75 and 150 kg ha-1) and bio-fertilizers on four levels (no inoculation, Azotobacter, Azospirillum and a combination of Azotobacter and Azospirillum). Results showed that nitrogen treatment had a significant effect on yield and yield components. Significant increase was observed in all characters with applying bio-fertilizers. Interaction of effect of nitrogen and bio-fertilizers treatments on seed yield showed when no nitrogen fertilizer was used, the highest seed yield was obtained from the combined use of bio-fertilizers. But with application of 150 N (kg ha-1), the highest seed yield was obtained when no bio-fertilizers were applied. The oil yield was also influenced by experimental treatments so that the highest oil yield was obtained from 75 and 150 kg ha-1 N treatments. The combined use of bio-fertilizers also was statistically superior to other treatments. According to findings of the present study, it can be concluded that farmers can obtain the same canola yield if they apply half the conventional allocation of nitrogen with bio-fertilizers.