Inoculation with Potassium Solubilizing Bacteria and Its Effect on the Medicinal Characteristics of Paris polyphylla var. yunnanensis

Potassium (K) use efficiency in Paris polyphylla var. yunnanensis production is relatively low, and the excessive use of K fertilization has negative environmental impacts. Bacterial isolates can effectively alleviate this situation. The present work aimed to analyze the effects of different combinations of three potassium-solubilizing bacteria (KSB) (Bacillus thuringiensis, B. polymyxa, and Paenibacillus amylolyticus) on K in soil and P. polyphylla var. yunnanensis. The results showed that the contents of different forms of K were increased after the application of KSB. Compared with the control group, the maximum increases of slow-acting K, available K, quick-acting K, exchangeable K, and water-soluble K were 32.6% under inoculation with both P. amylolyticus and B. polymyxa, 73.5% with B. thuringiensis, 114.0% with B. thuringiensis, 83.2% with P. amylolyticus, and 210.0% with B. thuringiensis, respectively. This promoted the conversion of soil K to the form of K with high plant availability. Pseudo-protodiosgenin and diosgenin H contents were improved by KSB inoculations, which promoted medicinal quality of P. polyphylla var. yunnanensis. Correlation analysis showed that there were significantly positive correlations among the five forms of K in the soil in all experimental groups. In conclusion, the inoculation of KSB effectively improved the plant availability of soil K and medicinal quality of P. polyphylla var. yunnanensis, providing a path for sustainable production of P. polyphylla var. yunnanensis.