Salt–Alkali-Resistant Phosphate-Solubilizing Bacterium: Kushneria sp. YCWA18 Improves Soil Available Phosphorus and Promotes the Growth of Suaeda salsa

Utilization of insoluble P in soils of salt–alkali regions is key to increasing available P content. P-solubilizing bacteria (PSB) dissolve inorganic phosphates or mineralize organic phosphates in the soil to promote plant growth. In this study, we analyzed the growth kinetics and salt–alkali tolerance of the halophilic PSB Kushneria sp. YCWA18. Suaeda salsa was used for assessing seed germination rate and growth of plants after inoculation with this PSB. Our results showed that the maximum P solubilized by the bacterium was 616.98 mg/L at 48 h. The available P content increased with time, with a simultaneous reduction in pH. YCWA18 grew well under 5% NaCl but exhibited average alkali resistance. YCWA18 promoted the seed germination of S. salsa which was otherwise inhibited under NaCl–alkali stress, but it had no effect under low NaCl or high alkali conditions. The addition of YCWA18 to salt–alkali soil led to a reduction in soil pH and a 1.5–tenfold increase in available P, plant height and biomass. Thus, YCWA18 improved P availability in salt–alkali soil and promoted plant growth. The results of our study provide a theoretical basis for the application of PSB in salt–alkali soils.