Fritillaria taipaiensis is a valuable traditional Chinese medicinal plant affected by germplasm degradation during cultivation. To find a suitable solution for this problem, F. taipaiensis was inoculated with exogenous arbuscular mycorrhiza (AM) fungi, potassium-solubilizing bacteria, and phosphorus-solubilizing bacteria in pot experiments. The effects of inoculation on the AM colonization, photosynthetic pigment, and superoxide dismutase contents, rhizospheric enzyme activities, alkaloid, and nucleotide content of F. taipaiensis were studied. The results showed that the inoculation increased mycorrhizal infection intensity of F. taipaiensis. Compared to the control group, the photosynthetic pigment contents in the leaf of the inoculation groups were increased; the content of soluble protein, the activities of the superoxide dismutase, catalase, and peroxidase in leaves were all significantly increased, and the content of malondialdehyde was decreased. The microbial inoculum also increased the content of active ingredients in F. taipaiensis bulbs and increased the enzyme activities, total microorganism number, bacteria/fungi, and actinomycetes/fungi ratios in the rhizosphere. To sum up, microbial fertilizer can significantly improve the rhizospheric environment and medicinal quality of F. taipaiensis. This research provides a theoretical basis and experimental evidence for the sustainable development of an F. taipaiensis industry.

Fritillaria taipaiensis is a valuable traditional Chinese medicinal plant that has experienced continuous decline over its cropping area. The present study aims to explore the reasons for the quality and growth decline. The fungal diversities and biochemical factors in its rhizospheric soils with cultivation duration from 1 up to 5 years were analyzed and compared. The results showed that rhizospheric fungi of F. taipaiensis belong to six phyla, including Neocallimastigomycota, Glomeromycota, Basidiomycota, Chytridiomycota, Zygomycota and Ascomycota. Thirteen genera (Pseudogymnoascus, Fusarium, Mortierella, Colletotrichum, Laetinaevia, Gibberella, Synchytrium, Lysurus, Trichocladium, Volutella, Monoblepharis, Aquamyces and Trichoderma) constituted the “core community” in the rhizosphere of F. taipaiensis. The dominant fungal genera varied significantly in rhizospheric soils with different cultivation years. The abundance of fungal species in the soil declined with the cultivation year generally. The pH, available P, organic matter and urease activity were the primary factors determining the fungal community composition in the rhizosphere. The content of organic matter, available N, P and K and the activities of urease and alkaline phosphatase decreased with cultivation years. The soil pH increased with cultivation years and was unsuitable for F. taipaiensis growth. These features suggested that long-term single planting altered the fungal community structure, fertility conditions and soil enzyme activities in F. taipaiensis rhizospheric soils, which could be detrimental for plant growth and quality.

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.