Paris polyphylla var. yunnanensis, a medicinal plant that originated in Yunnan (China), has been over-harvested in the wild population, resulting in its artificial cultivation. Given the negative environmental impacts of the excessive use of phosphorus (P) fertilization, the application of organophosphate-degrading bacteria (OPDB) is a sustainable approach for improving the P use efficiency in Paris polyphylla var. yunnanensis production. The present work aimed to analyze the effects of three organic phosphate-solubilizing bacteria of Bacillus on the yield and quality of P. polyphylla var. yunnanensis and the P concentrations in the soil. All the inoculation treatments distinctly increased the rhizome biomass, steroidal, and total saponin concentrations of the rhizomes and the Olsen-P and organic P in the soil. The highest growth rate of rhizomes biomass, steroidal saponins, available phosphorus, and total phosphorus content was seen in the S7 group, which was inoculated with all three OPDB strains, showing increases of 134.58%, 132.56%, 51.64%, and 17.19%, respectively. The highest total saponin content was found in the group inoculated with B. mycoides and B. wiedmannii, which increased by 33.68%. Moreover, the highest organic P content was seen in the group inoculated with B. wiedmannii and B. proteolyticus, which increased by 96.20%. In addition, the rhizome biomass was significantly positively correlated with the saponin concentration, together with the positive correlation between the Olsen-P and organic P and total P. It is concluded that inoculation with organophosphate-degrading bacteria improved the biomass and medicinal ingredients of the rhizome in P. polyphylla var. yunnanensis, coupled with increased soil P fertility, with a mixture of the three bacteria performing best.

To improve the phosphorus utilization efficiency and medicinal quality of the traditional Chinese medicinal herb Paris polyphylla var. yunnanensis, three inorganic phosphorus-solubilizing bacteria strains (Bacillus cereus Y1-1, Bacillus aryabhattai Z6-1, and Bacillus aryabhattai Z3-4) were inoculated individually and in combination into the rhizosphere soil of Paris polyphylla var. yunnanensis in a greenhouse pot experiment. At the late growth stage, the contents of total and inorganic phosphorus in the rhizosphere soils, as well as the total phosphorus and six steroidal saponins in the plants, were measured. The proportion of inorganic phosphorus in rhizosphere soils of treatment groups increased by 9.83~30.43%. The content of effective phosphorus form Ca₂-P in the rhizosphere soils of treatment groups increased by 50.81~328.37%. Inoculation with B. aryabhattai (S2, S3, and S6) significantly increased total steroidal saponin content in plants by 9.14%, 10.64%, and 16.58%, respectively. An antagonistic effect was observed when multiple bacterial strains were inoculated together. Thus, mixed inoculation was less effective than single-strain inoculation in improving rhizosphere soil phosphorus structure. In conclusion, inoculation with inorganic phosphorus-solubilizing bacteria could enhance phosphorus availability in rhizosphere soil and improve medicinal quality of Paris polyphylla var. yunnanensis. These findings provide a basis for efficient phosphorus resource utilization and sustainable cultivation to enhance medicinal plant quality.