Responses of Soybean Biomass and Bacterial Community Diversity of AMF Spore-Associated and Soybean Rhizosphere Soil to Microbial Inoculation and Chlorothalonil

Arbuscular mycorrhizal fungi (AMF) and phosphorus-solubilizing bacteria (PSB) play crucial roles in enhancing crop growth, increasing yields, and improving the soil microbial environment. The aim of this study was to investigate the effects of microbial inoculation and chlorothalonil on the AMF colonization rate in soybean roots, AMF spore density, nodule number, soybean biomass, and the composition of bacterial communities associated with soybean rhizosphere soil and AMF spores. The results indicated that the AMF colonization rate in soybean roots, AMF spore density, nodule number, and soybean biomass in the treatment inoculated with both Rhizophagus intraradices and Acinetobacter calcoaceticus were significantly greater than those in the other treatments. Inoculation with R. intraradices and A. calcoaceticus and spraying with chlorothalonil could influence the bacterial diversity in the rhizosphere soil of soybean. Compared with that in the control treatment, the relative abundance of Firmicutes in the rhizosphere soil of soybean plants inoculated with R. intraradices increased by 1.40%. In addition, both spraying with chlorothalonil and inoculation with A. calcoaceticus influenced the composition of AMF spore-associated bacterial communities. The relative abundance of Proteobacteria in AMF spore from soybean rhizosphere soil inoculated with R. intraradices and A. calcoaceticus increased by 12.42% compared to that in samples inoculated solely with A. calcoaceticus. This study provides a theoretical basis for microbial inoculation in improving the microenvironment of soybean rhizosphere soil and increasing soybean biomass.