Influence of Nitrogen Fertilizer Rates and Seed Inoculation with Plant Growth Promoting Rhizobacteria (PGPR) on Yield, Fertilizer Use Efficiency, Rate and Effective Grain Filling Period of Soybean (Glycine max L.) in Second Cropping

In order to study of effects of nitrogen fertilizer and seed inoculation with plant growth promoting rhizobacteria (PGPR) on yield، fertilizer use efficiency، rate and effective grain filling period of soybean (Glycine max L.)، a factorial experiment was conducted based on randomized complete block design with three replications in 25 km Gorgan at Golestan province in 2011. Factors were different rates of nitrogen fertilizer in four levels (without nitrogen and application 25، 50 and 75 kg urea/ha) and seed inoculation with plant growth promoting rhizobacteria in five levels (without inoculation، seed inoculation with Pseudomonas putida strain 41، Pseudomonas putida strain 186، Azotobacter chroococoum strain 5 and Bradyrhizobium japonicum). The results showed that nitrogen fertilizer rates and seed inoculation with PGPR had significantly effects on grain yield، grain 100 weight، number of seeds per plant، plant height and all of grain filling parameters. Maximum of grain yield and grain filling period were obtained in application of 75 kg urea/ha × seed inoculation with Bradyrhizobium japonicum. Seed inoculation with plant growth promoting rhizobacteria and Bradyrhizobium japonicum increased nitrogen use efficiency compared to no seed inoculation. Of course، the highest nitrogen use efficiency belonged to seed inoculation with Brady rhizobium japonicum. Means comparison showed that maximum of nitrogen use efficiency was obtained in application of 25 kg urea/ha×seed inoculation with Bradyrhizobium japonicum and minimum of it was obtained in application of 75 kg urea /ha × no seed inoculation. It seems that in order to increasing of grain yield and the other traits (except nitrogen use efficiency) can be suggested that be applied seed inoculation with Bradyrhizobium japonicum × application of 75 kg urea /ha in second cropping of soybean.