Phenolic acid reduction in Fritillaria taipaiensis rhizosphere via organic fertilization.

Fritillaria taipaiensis is a valuable traditional Chinese medicinal plant that is prone to germplasm degradation during long-term continuous monoculture. Allelopathic autotoxicity, which is mediated primarily by phenolic acids, is considered a major factor contributing to this degradation. To reveal the accumulation patterns of phenolic acids in the rhizospheric soil of F. taipaiensis under continuous monoculture, five phenolic acids (p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, and ferulic acid) in the rhizospheric soil of F. taipaiensis across 1-5 y, and various fertilizer regimes (chemical fertilizer, chemical fertilizer + organic fertilizer, and organic fertilizer) were determined to assess their accumulation characteristics, along with soil fertility parameters. The result showed that the levels of available nitrogen, Olsen-phosphorus, and available potassium in chemical fertilizer and chemical fertilizer + organic fertilizer, along with the organic matter content in all three soil samples, showed a decreasing trend over time, while organic fertilizer exhibited significant fluctuations without a clear pattern. The phenolic acid content in the rhizospheric soil initially increased and then generally decreased in later stages. After 5 y of cultivation, the soils treated with organic fertilizer exhibited lower phenolic acid levels than those treated with chemical fertilizer. The accumulation patterns of individual phenolic acids varied with fertilizer type and cultivation period, with organic fertilizer showing the most consistent patterns across all phenolic acids. There was a positive correlation among the five phenolic acids, along with a significant positive correlation between soil organic matter and vanillic acid and ferulic acid. These findings suggest that long-term monoculture leads to distinct accumulation characteristics of phenolic acids in the rhizospheric soil of F. taipaiensis, and the application of organic fertilizer can mitigate such accumulation.