ITS of different exogenous phenolic acids alter the soil metabolites and microbial communities of Panax notoginseng from the forest understory

ITS of different exogenous phenolic acids alter the soil metabolites and microbial communities of Panax notoginseng from the forest understory.Large-scale intensive cultivation of Panax notoginseng in agricultural systems, which led to a prominent problem of the continuous cropping obstacles in Yunnan, China. However, it is not clear whether continuous cropping obstacles existed in agroforestry systems, especially the Panax ginseng-pinus agroforestry system with organic management. In this paper, the application of three types of exogenous phenolic acids (phthalic acid, palmitic acid and phthalic + palmitic mixed acids) was used to simulate the continuous cropping obstacles, compare and analyze the changes and interrelations among plants, soil physicochemical properties, soil microbes and soil metabolites. The results showed that mixed phenolic acids rather than single phenolic acids had stronger inhibitory effect on the growth of Panax notoginseng, and significantly differences were observed in the change of soil characterization under different phenolic acids treatment. Moreover, the soil microbial diversity of Panax notoginseng affected by the different phenolic acids were different in terms of time (phthalic acid), concentration (mixed acid) and microbial species (palmitic acid). The application of exogenous phenolic acids altered the dominant but not the core flora of soil bacteria and fungi. Meanwhile, phthalic + palmitic mixed acids application had the greatest effect on soil differential metabolites. In addition, SEM analysis showed that plants, soil edaphic factors, and soil metabolites as direct or indirect factors have different degrees of influence on soil microorganisms under different phenolic acid conditions. Our study provides evaluation indicators for occurring possible the continuous cropping obstacles in Panax notoginseng-pinus agroforestry systems.