Allelochemical detection from rhizosphere soil of continuous-cropping Panax notoginseng and effects of the extracts on seed germination of three crops

ObjectiveEffects of allelochemicals in Panax notoginseng rhizosphere soil and soil extract on germina-tion of different seeds were studied in order to provide reference for revealing allelopathy mechanism of continuous cro-pping P. notoginseng rhizosphere soil. MethodThe species and concentration of allelochemicals from uncultivated soil, soil of one-year-cropping,soil of two years-cropping and soil of three years-cropping were examined through high perfor-mance liquid chromatogrophy(HPLC) method. Effects of soil extracts on seed germination of rape,corn and Chinese ca-bbage were analyzed by bioassay method. ResultPhenolic acid compounds were detected in P. notoginseng rhizosphere soil with different cropping years. As cropping years increased, the contents of most phenolic acid compounds except cin-namic acid showed an decreasing trend compared with uncultivated soil(judged from peak area), but there was no obvious regulation. Under the same cropping year, as concentration of soil extracts increased, the seed germination rate of the three crops rose as a whole. When the concentrations of soil extracts were the same, the effects of extracts from soil of three-year-cropping on seed germination were more obvious than others. When extracted by different solvents, as concen-tration of soil extracts increased, germination rate, germination potential and germination index of the three crops began to vary. Most of the indexes were enhanced as concentration of solvents increased. ConclusionMost phenolic acid com-pounds in P. notoginseng rhizosphere soil with different cropping years may not be the main allelochemicals. The soil ex-tracts show concentration dependence on seeds germination.