Effect of Microbial Inoculants on Rhizosphere Soil Microbial Community Structure in Melon

The rhizosphere microbial community of melon (Cucumis melo L.) plays an important role in soil nutrient transformation and plant growth. The application of microbial inoculants is an effective approach for regulating rhizosphere microecology and improving soil nutrient availability. In this study, Bacillus altitudinis and Rhodopseudomonas palustris were applied to melon plants during the vine extension stage. Soil physicochemical analysis and metagenomic sequencing of rhizosphere soil microorganisms using the DNBSEQ-T7 sequencing platform were conducted to investigate the effects of microbial inoculants on soil nutrients, bacterial community diversity, and community structure. The results showed that microbial inoculant application effectively altered soil physicochemical properties and affected rhizosphere bacterial diversity and community structure, while not substantially changing the overall composition of dominant bacterial phyla. Redundancy analysis indicated that bacterial community structure was positively associated with AK and NO3−-N, but negatively associated with Cl− following microbial inoculant application. Metagenomic analysis revealed that the microbial inoculants used in this study did not substantially alter the overall functional structure of the microbial community, but only showed the potential to modulate specific functions. In summary, this study provides a theoretical basis for improving the physicochemical properties of melon rhizosphere soil and regulating rhizosphere microbial community structure through the application of microbial inoculants.