Effects of Increasing Microbial Fertilizers on Phenolic Acids in Fritillaria taipaiensis P. Y. Li Soil

To investigate the effect of microbial fertilizers on phenolic acids in the cultivation soil of Fritillaria taipaiensis P. Y. Li, a quantitative approach utilizing ultra-high-performance liquid chromatography was applied to assess the phenolic acid levels in both rhizosphere and non-rhizosphere soils of F. taipaiensis P. Y. Li under five different microbial fertilizer regimes. Detection of six key phenolic acids (p-hydroxybenzoic, p-coumaric, vanillic, syringic, chlorogenic, and ferulic) was consistent in all soil samples, regardless of rhizosphere status or inoculation treatment. Among these, chlorogenic acid had the highest content in both rhizosphere (17.651 μg/g, accounting for 55.51%) and non-rhizosphere (25.975 μg/g, accounting for 42.38%) soils, while vanillic acid (0.903 μg/g, accounting for 8.27% in rhizosphere soil) and p-hydroxybenzoic acid (0.086 μg/g, accounting for 1.34% in non-rhizosphere soil) were the lowest in their respective soils. Whereas the control (CK) showed higher levels, inoculation with Claroideoglomus claroideum resulted in a marked decrease in all six phenolic acids within the F. taipaiensis soil. In contrast, the other treatment groups exhibited higher overall phenolic acid content than CK. Correlation analysis indicated a subset of significant positive correlations among phenolic acids in the non-rhizosphere soil; by contrast, their intercorrelations within the rhizosphere soil were universally positive and significant. The phenolic acid content in F. taipaiensis soil was significantly altered by the application of different microbial fertilizers. Among them, C. claroideum was the most effective in reducing phenolic acid accumulation.