Abstract

IntroductionMicroorganisms are capable of enhancing plant growth by improving the soil microenvironment, supplying nutrients, and facilitating root development. Different microorganisms employ distinct mechanisms to achieve promotion of plant growth.MethodsThis study employed a partitioned plastic greenhouse experiment with three treatments—Chlorella sorokiniana (C. sorokiniana) inoculation, a Bacillus combination inoculation, and a water control—applied via root irrigation at each tomato growth stage, aiming to investigate the effects of C. sorokiniana and Bacillus combination on tomato growth, rhizosphere soil properties, and associated microbial communities.ResultsThe results demonstrated that the combination of C. sorokiniana and Bacillus significantly promoted plant growth and improved soil quality. C. sorokiniana primarily enhanced soil physicochemical properties, as evidenced by a 53.68% decrease in electrical conductivity (EC). It also increased the activities of key soil nitrogen cycle-related enzymes, including urease (42.34%) and protease (24.14%), and elevated soil organic carbon (SOC) content (19.39%). Collectively, these modifications in soil conditions contributed to enhanced plant growth, resulting in increased plant height (11.72%) and stem diameter (9.78%). In contrast, the Bacillus combination enhanced soil nutrient availability (alkaline-hydrolyzable nitrogen (AN) 5.55%, available phosphorus (AP) 21.57%, available potassium (AK) 6.53%) by modulating the structure and function of the soil microbial community. Furthermore, it positively regulated the concentrations of metal ions (Ca2+ 0.51%, Mg2+ 1.99%), increased stress resistance in tomato plants (peroxidase (POD) 66.18%, superoxide dismutase (SOD) 98.67%, and catalase (CAT) 31.79%), and consequently enhanced plant growth metrics, including height (17.36%) and stem diameter (18.36%). These changes