Effect And Intervention Panax Rhizosphere Soil Allelopathic Phenolic Acids

Objective:This study meanly explores the type of phenolic acids in Panax Notoginseng rhizosphere soil and their allelopathic effects on Panax Notoginseng and how the nutritional condition affects the content of the phenolic acids and whether the wheat and Panax Notoginseng rotation is reasonable.Methods:This study employs the technology of HPLC-MS and HPLC to identify the phenolic acids of Panax Notoginseng rhizosphere soil. The cultivation experiment of Panax Notoginseng under different nutritional conditions was arranged. And we collected samples of the plant of Panax Notoginseng and the rhizosphere soil in April, August and December. Then, the contents of the phenolic acids in rhizosphere soil were measured. The6phenolic acids measured were tested the allelopathic effects on wheat seeds and Panax Notoginseng seeds.Results:1. Compared with the MS prints of reference compounds and sample, it could confirm that there exited p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid and benzoic acid in the fraction of Panax Notoginseng rhizosphere soil, p-coumaric acid had the highest content and the syringic acid had the lowest content in the3-year-old Panax Notoginseng rhizosphere soil,and the content of total phenolic acids was more than1000μg· g-1,much higher than the new soil. Furthermore, with the increase of planting years, the content of total phenolic acids showed a significant growth trend.The content order of the6phenolic acids in the Panax Notoginseng rhizosphere soil were:p-coumaric acid> benzoic acid> vanillic acid>ferulic acid> p-hydroxybenzoic acid> syringic acid.2. In the six kinds of phenolic acids measured in the rhizosphere soil of Panax Notoginseng, under the concentration range tested, benzoic acid had the strongest inhibition of the wheat, and ferulic acid had the strongest inhibition of Panax Notoginseng, which showed that different species had different tolerance for the same kind acid. The impact of mixed acids to the growth of wheat seedlings showed low concentrations promoted and high concentrations inhibited trend. The mixed acid showed great impact on wheat root length, where in the mixed concentration of A performed significantly inhibited, while in the mixed concentration C, D, E, then showed significantly promotion. The mixed acid on the growth of Panax Notoginseng seedlings showed suppression after the first promotion, and then suppress again promote, like the M-type curve with the concentration increased.3. The allelopathy that the mixed acids showed on the wheat and Panax Notoginseng was accordant, that was the mixed acids had a strong inhibitory effect on the height of seedling, and the next successively were germination rate, root length. The mixed acid within the concentration range tested had a higher inhibition on Panax than that on wheat.The mixed acids concentrations measured in the2-year-old Panax rhizosphere soil strongly inhibited the growth of Panax Notoginseng, and obviously promoted the growth of wheat, then it could confirm that the rotation between wheat crop and Panax Notoginseng is feasible.Conclusions:This paper for the first time detected p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid and benzoic acid in the Panax Notoginseng rhizosphere soil and for the first time studied how fertilizer type and amount of fertilizer impacted the content in the Panax Notoginseng rhizosphere soil. After allelopathy testing, it could confirm that the phenolic acid concentration in the Panax Notoginseng rhizosphere soil can inhibit the growth of Panax Notoginseng. We concluded that the increment of phenolic acid maybe the important reason for the cropping obstacles of Panax Notoginseng.