Effects of Rhizophagus intraradices on soybean yield and the composition of microbial communities in the rhizosphere soil of continuous cropping soybean.

Soybean (Glycine max L.) is an important oil and economic crop in the world. However, soybean continuous cropping may lead to the decline of soybean yield and quality. The purpose of this study was to investigate the effects of Rhizophagus intraradices on soybean growth/yield, root rot disease index, and the composition of microbial communities in the rhizosphere soil of continuous cropping soybean at the R8 stage. The results showed that the 100-seed weight, seed-yield per plant, yield per 0.04 hectare, pods per plant, seed number per plant, branch number, plant height, and fresh weight of root and shoot, and disease index of soybean root rot were significantly affected by the inoculation of R. intraradices and soybean continuous cropping. The growth/yield indexes of soybean were the highest in the inoculated soybean plants under non-continuous cropping. Inoculation of R. intraradices and soybean continuous cropping significantly decreased and increased the disease index of soybean root rot, respectively. Bacterial diversity levels in the rhizosphere soil of continuous cropping soybean were lower than those in non-continuous cropping soybean. Furthermore, it also showed that inoculation of R. intraradices could increase the bacterial and fungal diversity in rhizosphere soil of soybean. It also showed that both inoculation and soybean continuous cropping had effects on the composition of microbial communities in the rhizosphere soil of soybean. Proteobacteria and Ascomycota were the most dominant bacterial and fungal phylum in all samples, respectively. The results would contribute to evaluating the biocontrol potential of R. intraradices against soybean root rot disease, increase soybean yield and improve the composition of microbial communities in the rhizosphere soil of continuous cropping soybean.