The influence of exogenous phenolic acid on plant, soil enzyme and soil microorganism can predict continuous cropping obstacle of Panax notoginseng under the forest

Panax pseudoginseng suffers from severe cropping obstacles under conventional cropping patterns; however, it is not clear whether continuous cropping obstacles existed in organic Panax pseudoginseng cultivation in a pine - Panax pseudoginseng agroforestry complex system. In this study, we used phenolic acids (phthalic acid, palmitic acid, stearic acid, ferulic acid) derived from Panax ginseng root secretions to simulate the cropping obstacles by exogenously applying different concentrations of mixed phenolic acids, and explored the changes in the growth, soil physicochemical properties, soil enzyme activities and microbial diversity of Panax ginseng in the forest under the conditions of exogenous phenolic acids and the direct relationship between them. The results showed that the dry and fresh weight of plants, soil physicochemical properties (pH, SOC, NH4+-N, NO3--N, TK) and soil extracellular enzyme activities (AG, BG, NAG, XYL) tended to decrease under simulated cropping obstacles conditions at high concentrations (>150 mg/kg) rather than low concentrations (150 mg/kg in Panax notoginseng soils imply a significant cropping obstacles and we suggest that Panax notoginseng should no longer be planted. This study provides a theoretical basis for the planting of panax pseudoginseng in the forest and the sustainable development of the pine - panax pseudoginseng agroforestry complex