Effect of mycorrhiza and bradyrhizobium on yield and yield components of soybean in different amounts of nitrogen fertilizer

In order to study the effect of mycorrhiza and bradyrhizobium on yield and yield components of soybean under different amounts of starter nitrogen fertilizer, a field experiment was conducted at the agricultural research station, Bu-Ali Sina University in 2015 growing season. A factorial experiment based on randomized complete block design was arranged with three replications. Experiment factors included three levels of starter nitrogen fertilizer including 0, 30 and 60 kg ha-1, bradyrhizobium including inoculated and non-inoculated and mycorrhiza including application and non-application. Results indicated that plant height, number of leaves per plant, yield and yield components and biological yield of soybean and mycorrhizal colonization percentage affected by interaction of studied factors. At all levels of starter nitrogen, interaction between bradyrhizobium and mycorrhiza increased number pod per plant and 1000 seed weight. Application of 60 kg ha-1 nitrogen decreased colonization percentage by 20.22 % compared to no application nitrogen treatment. Application of both bio-fertilizers with 30 kg ha-1 nitrogen gave the highest grain and biological yields (511.67 g m-2 and 1223.16 g m-2 respectively). So to improve soybean performance and reduce the nitrogen fertilizer consumption, it is recommended that both fertilizers to be taken simultaneously with 30 kg ha-1 nitrogen as starter.