Application of rhizobacteria to improve microbial community structure and maize (Zea mays L.) growth in saline soil

The utilization of plant growth-promoting rhizobacteria (PGPR) has emerged as a prominent focus in contemporary research on soil microbiology, microecology, and plant stress tolerance. However, how PGPR influence the soil bacterial community and related ecological functions remains unclear. The aim of this study was to investigate the effects of three natural PGPR inoculations (YL07, Planococcus soli WZYH02; YL10, Bacillus atrophaeus WZYH01; YL0710, Planococcus soli WZYH02 and Bacillus atrophaeus WZYH01) on maize (Zea mays L.) growth under two salt stress conditions (S1, EC_e = 2.1 ~ 2.5 dS/m; S2, EC_e = 5.5 ~ 5.9 dS/m). The results revealed that compared to the control (CK), the average plant height of maize seedlings significantly increased by 27%, 23%, and 29% with YL07, YL10, and YL0710 inoculation under S1 conditions, respectively, and increased by 30%, 20%, and 18% under S2 conditions, respectively. Moreover, PGPR inoculation positively influenced the content of superoxide dismutase, catalase, soluble sugar, and proline in maize under salt stress. Subsequent analysis of alpha diversity indices, relative microbial abundance, principal coordinate analysis, cladograms, and linear discriminant analysis effect size histograms indicated significant alterations in the rhizosphere microbial community due to PGPR inoculation. FAPROTAX analysis demonstrated that YL10 inoculation in S2 rhizosphere soil had a notable impact on carbon cycle functions, specifically chemoheterotrophy, fermentation, and phototrophy. Thus, this study provides evidence that PGPR inoculation improves soil microbial communities and plant indices under salt stress. These findings shed light on the potential of PGPR as a viable approach for enhancing plant stress tolerance and fostering sustainable agricultural practices.