Abstract: High total P content but insufficient available P in soil is an obstacle that restricts the efficient utilization of P in saline-alkali soil regions. Although saline-alkali resistant P-solubilizing bacteria (PSB) solubilize insoluble P, few studies have focused on their application in plant growth. We isolated a PSB strain, identified as Bacillus sp. DYS211, from bird droppings in saline-alkali regions and determined its growth characteristics and resistance to salt and alkalis. To investigate the effect of PSB on the germination and growth of plant seeds, we performed a potting experiment using Suaeda salsa with PSB added. The PSB strain grew rapidly in the first 12 h, and the solubilized P content from PSB reached a maximum of 258.22 mg L^-1 at 48 h. Saline-alkali tolerance and P-solubilizing ability tests showed that Bacillus sp. DYS211 preferred to dissolve inorganic P, was halophilic, and had a good P-solubilizing effect at 1%-8% salinity (available P > 150 mg L^-1). It exhibited good P solubilization abilities when glucose and sucrose were used as C sources or when ammonium sulfate, ammonium nitrate or yeast extract powder were used as N sources. In the growth promotion test, PSB increased seed germination, particularly under high-salinity stress, with a growth promotion of 8.33%. The PSB also improved the growth of S. salsa, including plant height and biomass (up to three times) under both saline and alkaline conditions, and the stem diameter increased under high-salinity stress. This strain demonstrates potential for vegetation restoration in saline-alkali regions.

Key words: available phosphorus, phosphate-solubilizing bacteria, Suaeda salsa, seed germination, plant biomass