Effect of arbuscular mycorrhiza and Bradyrhizobium japonicum on soybean yield and yield components under water stress

To evaluate the effect of biofertilizers on yield and yield components of a soybean cultivar (M9) under water stress condition، a study was carried out in a split plot randomized complete block design with three replications at research station of Bu Ali Sina university in 2012. The main plots included three levels of irrigation after 50، 100 and 150 mm evaporation from A pan and subplots included four biofertilizer treatments (Bradyrhizobium japonicum، arbuscular mycorrhizae، both biofertilizers and no biofertilizer). Results showed a significant effect of water deficit on number of pods per area، grains per pod، plant height، biological yield، grain and oil yields but seed weight، harvest index and oil percent were not affected. In the absence of moisture stress، biofertilizers had no significant effect on the most of traits even mycorrhizae reduced the plant height. Greatest reduction in soybean yield was observed in severe stress but the use of biofertilizers especially in both biofertilizers the negative effect of water stress minimized. So، the number of pods per area، seed weight، plant height، biological yield، grain and oil yields increased، respectively 33، 9. 6، 15. 4، 90، 93 and 170 percent compared to severe water stress in no- biofertilizers treatment.