Correlation Analysis of Soil Microbial Communities and Physicochemical Properties with Growth Characteristics of Medicago ruthenica in Different Habitats.

The aim of this study was to investigate the correlations between the morphology and microbial community structure of Medicago ruthenica and soil environmental factors. Soil samples were collected from M. ruthenica and from rhizosphere and non-rhizosphere soils under typical grasslands (C1), desertified grasslands (C2) and wetland meadows (C3). The morphological characteristics, soil physicochemical properties and enzyme activities of M. ruthenica varied significantly (P < 0.05) across the different habitats. Branch length and stem diameter were greatest in the C2 plot, and leaf area and leaf volume were greatest in the C3 plot. The contents of organic matter, alkaline dissolved nitrogen and quick-acting potassium, as well as the activities of soil sucrase and soil phosphatase, were ranked in the order of C3 > C1 > C2. The microbial community composition also varies by habitat. The dominant bacterial phyla were Proteobacteria, Actinobacteria, and Acidobacteria, and the fungal phyla were Ascomycota, Basidiomycota, and Mortierellomycota. The major metabolic pathways of bacteria and fungi in different habitats include biosynthesis, degradation/utilisation/assimilation and generation of precursor metabolites and energy. The bacterial phyla were significantly correlated with soil moisture, sucrase, catalase, and urease (P < 0.05), whereas the fungal phyla were significantly correlated with soil catalase (P < 0.05). In addition, the morphological characteristics of M. ruthenica are significantly correlated with soil moisture, catalase, phosphatase, available potassium, Actinobacteria, Myxococcota, and Patescibacteria. These findings indicate that soil microorganisms, soil physical and chemical properties, and enzyme activities in different habitats are related to structural characteristics, which in turn can affect the morphology of M. ruthenica.