Allelopathic Effect Of Active Substance From Paris Polyphylla Var.yunnanensis On Four Ornamental Herbaceous Herbs

The indoor petri dish method was used to study the effects of water extracts from Paris polyphylla root and leaf-stem on seed germination of the four ornamental herbaceous plant(Tagetes patula,Salvia japonica,Festuca arundinacea,Trifolium repens),simulating rainfall leaching.Then,we studied the effect and allelopathy mechanism of aqueous extracts from P.polyphylla leaf-stem on growth of four ornamental herbaceous plant seedlings via sand culture.Next,the potential allelochemicals of aqueous extracts from P.polyphylla leaf-stem were isolated with the systematic solvent method,from which different organic phases were obtain.The chemical compositions was determined of different phases with gas chromatographymass spectrometry(GC-MS).Last,the effect of different phases(petroleum acetate extract,aether extract,ethyl acetate extract,methanol extract and water extract)on seed germination of Chinese cabbage(Brassica pekinensis)were studied,the allelopathic activity of different phases were discussed.The main results were showed as follows:1.Allelopathy of different organs(root,leaf-stem)of P.polyphylla had different effects on four ornamental herbaceous plant,the allelopathic activity varied according to the species of acceptor plant,extract sources and extract concentrations.The aqueous extract from the two organs of P.polyphylla had inhibitory effects on germination of four species,leaf-stem showed a stronger allelopathy effect than root;when the concentration of aqueous extract increased,the inhibition enhanced gradually;The order of the alleiopathic sensitivity of water extractions from the two organs of P.polyphylla on 4plant species is T.repens > F.arundinacea > S.japonica > T.patula.Therefore,P.polyphylla had allelopathic effects to these 4 recipient plants;Allelochemicals were widely distributed in root and leaf-stem of P.polyphylla,but leaf-stem may be an important storage tissue of P.polyphylla Allelochemicals.2.The allelopathic effects of aqueous extracts from P.polyphylla leaf-stem on seedling growth of four ornamental herbaceous plant were different,and the allelopathy of different indexes of the same plant was different under the same concentration.In the range of experimental concentration,the water extract from leaf-stem of P.polyphylla showed a promoting effect on the seedling growth of T.patula;The seedling growth of S.japonica and F.arundinacea were always inhibited;But,the seedling growth of T.repens was stimulated by a low concentration(0.02-0.06g/ml)of P.polyphylla extract solution,but inhibited by a high concentration(0.08g/ml).Under the same concentration,the sensitivity of the three indexes of the same plant was: fresh weight > seedling height > root length.The allelopathy of P.polyphylla was characterized by species selection and concentration dependent tolerance.T.patula and T.repens could be used as herbaceous plants in combination with P.polyphylla.3.The relative electrical conductivity,protective enzyme activity(SOD、POD、CAT),MDA content,chlorophyll content,soluble protein content and root activity of four kinds of recipient plants were measured.With the increase of the concentration of water extract,the relative electrical conductivity and activity of POD,MDA content,soluble protein content,chlorophyll content and root activity of T.patula showed an increasing trend.However,the activity of SOD showed a decreasing trend,and the activity of CAT increased at first and then decreased;The soluble protein and root activity of S.japonica showed an decreasing trend,the activity of CAT increased first and then decreased,and the other indexes showed an increasing trend;The relative conductivity,POD activity,and CAT activity of F.arundinacea showed an increasing trend.The MDA content,SOD activity increased first and then decreased.The critical threshold was 0.06 g / ml,chlorophyll content,soluble protein content and root activity showed a decreasing trend;The root activity of T.repens increased at first and then decreased,the critical threshold was 0.04 g / ml,and the other indexes showed an increasing trend.The results showed that the aqueous extract of P.polyphylla could affect the growth of recipient plants by affecting the antioxidant enzyme activity,cell membrane permeability,protein synthesis,photosynthesis and root activity.4.The chemical constituents of aqueous extracts from leaf-stem of P.polyphylla were identified by gas chromatography-mass spectrometry(GC-MS).12 substances were detected in petroleum ether phase,17 substances were detected in ether phase,23 substances were detected in ethyl acetate phase,6 substances were detected in methanol phase and 7 substances were detected in deionized water phase.The germination rate of Chinese cabbage(Brassica pekinensis)was significantly inhibited by The five isolates of aqueous extracts from leaf-stem of P.polyphylla.The inhibitory effect was in the following order: methanol phase > aqueous phase > ethyl acetate phase > ether phase > petroleum ether phase.It is inferred that allelochemicals exist in all the five phases,but the allelochemicals in methanol phase may be the main allelochemicals in leaf-stem of P.polyphylla.