Abstract: Soil salinization is a widespread abiotic stress globally, profoundly impacting plant distribution and ecosystem stability. Alterations in rhizosphere microorganisms can serve as indicators of changes in the soil environment and can enhance plant stress resistance through symbiotic interactions. In this study, two soybean cultivars, “Heihe 49” (HH49, saline-alkali tolerant) and “Henong 95” (HN95, saline-alkali sensitive) were grown in the pots filled with soda saline-alkali soil (pH 9.23, electrical conductivity 94.13 μS·cm^-1) for 90 days. We investigated the effects of different soybean cultivars on the physical and chemical properties of soda saline-alkali soil and bacterial community structure. The results showed that both soybean cultivars significantly reduced soil pH, electrical conductivity, and alkali-hydrolyzable nitrogen content in the rhizosphere soil of soybean plants, but significantly increased the available potassium content, bacterial abundance and diversity. The abundance and diversity of bacterial communities in the rhizosphere soil of HH49 were significantly higher than those of HN95. Strains such as OLB17 (sp902826795), Bradyrhizobium daqingense, Xanthobacter flavus, Sphingopyxis (sp000756385), Aquabacterium A terrae, Arenimonas terrae, and Pseudoxanthomonas A wuyuanensis were significantly enriched in the rhizosphere soil of HH49 plants, which showed a significant positive correlation with soil pH, electrical conductivity, alkali-hydrolyzable nitrogen, and available potassium content. Redundancy analysis (RDA) results showed that Sphingopyxis (sp000756385) (F=60.1, P=0.008) and Pseudoxanthomonas A wuyuanensis (F=43.0, P=0.064) played a major role in influencing soil physical and chemical properties. The significant enrichment of the above-mentioned microorganisms in the rhizosphere soil of soybeans is conducive to promoting soil nutrient transformation, reducing soil pH, and improving the growth and stress resistance of soybean plants.

Key words: soybean, saline-alkaline stress, bacteria, diversity, metagenome