Spatiotemporal dynamics of rhizosphere microbial communities in alfalfa across saline-alkali agro-ecosystems

The rhizosphere represents a highly active plant–soil interface, where microorganisms play critical roles in the growth and development of alfalfa and in regulating local ecosystem processes. However, the mechanisms by which alfalfa rhizosphere microorganisms respond to spatiotemporal variation in saline–alkali environments remain poorly understood. Here, we collected alfalfa plants from one- to eight-year-old stands across three pastoral regions differing in soil type and characterized their rhizosphere soils. Using soil physicochemical analyzes, soil enzymology, and metagenomics, we examined how rhizosphere microbial communities respond to temporal and spatial variation in saline–alkali soils. Our findings indicate that alfalfa rhizosphere microecology may maintain rhizosphere health by modulating soil physicochemical properties, reducing peroxidase activity, enhancing reductase activity, and increasing the abundance of beneficial microorganisms. These results underscore the potential value of introducing exogenous beneficial bacteria to shape indigenous rhizosphere microecology.