Mineral-Solubilizing Microbial Inoculums Promote Robinia Pseudoacacia L. Growth By Optimizing Rhizospheric Soil Microbial Community Structure

Abstract

The application of mineral-solubilizing microbial inoculums is a biological strategy used for the restoration of vegetation at rock mining sites. These inoculums improve soil fertility, enhance plant growth, and accelerate soil weathering. However, their impacts on rhizospheric soil microbial communities are not well understood. This study aimed to elucidate how various mineral-solubilizing microbial inoculums affected the root systems of R. pseudoacacia. A pot experiment was conducted, and 32 samples were extracted from four different mineral-solubilizing microbial inoculum treatments to investigate the responses of soil bacterial and fungal communities in the rhizospheres of R. pseudoacacia. The results showed that the impacts of the inoculums on fungal community structures surpassed those of the bacterial communities. The relative abundance of Proteobacteria increased, which was strongly correlated with root nodulation. Interestingly, the inoculums significantly influenced the diversity and evenness of bacterial communities in the rhizospheric soil. Correlation analysis revealed positive correlations between Proteobacteria, Verrucomicrobia, Ascomycota, Zoopagomycota, soil enzyme activities, and plant growth. RDA analysis indicated that the relative abundance of these bacterial and fungal phyla positively influenced root nodulation. This study suggests that the application of mineral-solubilizing microbial inoculums optimizes the rhizospheric soil microbial community structure, promotes R. pseudoacacia root nodulation, and enhance the nitrogen fixation capacities of plants. Further, it provides a theoretical foundation for the application of mineral-solubilizing microbial inoculums for slope ecological restoration.