SRP403118 PRJNA891373 Study on the microbiological mechanism of compound microbial fertilizer alleviating rice growth stress in saline soil Long-term soil salinization can easily lead to soil degradation, resulting in soil compaction, soil nutrient imbalance, soil microbial diversity reduction, and even aggravating crop diseases and soil-borne diseases. Microbial remediation is one of the important measures to improve saline soil. Starting from the fact that compound microbial fertilizer significantly alleviated rice growth stress and increased rice yield in saline soil, this study explored the effects of compound microbial fertilizer on rice rhizosphere soil microbial diversity and community structure, and analyzed the correlation between microbial community composition and soil available nutrient factors. Furthermore, the microbial mechanism of compound microbial fertilizer alleviating the growth stress and improving the fertilizer supply capacity of rice in saline soil was revealed. The results showed that the application of compound microbial fertilizer significantly increased the contents of soil available nitrogen (AN), available phosphorus (AP) and available potassium (AK) (p < 0.05), and significantly increased the rice yield (p < 0.05). Moreover, soil salt content was significantly decreased (p < 0.05). In addition, the application of compound microbial fertilizer significantly increased soil microbial diversity and reshaped the composition of microbial community structure. LEfSe (LDA Effect Size) analysis showed that the relative abundance of 13 genera, 6 families and 3 purposes in the control group and the experimental group were significantly different (p < 0.05). The results of redundancy analysis showed that available potassium (AK) and cation exchange capacity (CEC) were the key factors affecting microbial community structure. These results can provide theoretical basises for the improvement of saline land.