Study On The Mechanism Of Root-rot Occurred In Panax Notoginseng And The Preventive Effect Of Artemisia Annua

Purpose:This research through measuring the changes of Chinese herbal medicine quality and allelochemicals in rhizosphere soil of Panax notoginseng after root-rot occurred in P.notoginseng to unveil the occurrence mechanism of roo-rot.And covering Artemisia annua on P.notoginseng siol surface could inhibit the occurence of root-rot,meanwhile promote plant growth of P.notoginseng.This study mainly explored the mechanism of allelochemicals and water soluble extract from A.annua leaves on the growth of Fusarium oxysporum by vitro experiment.Methods:1.Measured biological character indexes of healthy group and diseased group of P.notoginseng,and detected the change of different parts saponins content.2.Determined the kinds and allelochemicals content of organic acids and phenolic acids?PAs?from rhizosphere soil.3.Based on the determinated PAs kinds and content from rhizosphere soil,by vitro experiment,detected the influences of exogenous PAs on F.oxysporum mycelia growth,spore yields and toxin production.4.Through the vitro experiment to study the effect of water soluble extract from A.annua leaves on F.oxysporum mycelia diameter,spore yields,hypha dry weight and fusaric acid production.Results:1.Different groups of P.notoginseng biological character and saponins content determination results showed that all biological characters had different levels decreased after infected by pathogenic and diseased,of which,the leaf fresh weight was injury heavist,and closely followed by leaf area.After diseased,compared with healthy plants,the content of ginsenoside Rb₁ and ginsenoside Rd was increased,nevertheless ginsenoside Rg₁'s content was reduced.2.The kind and content of llelochemical from rhizosphere soil determination results indicated that the presence of allelochemicals in the rhizosphere soils of P.notoginseng,whose contents in the rhizosphere soils of healthy plants were higher than those of the diseased ones to some extent.There were 5 kinds of PAs detected,the content of which was p-coumaric acid>p-hydroxybenzoic acid>vanillic acid>ferulic acid>syringic acid,and all showed significant difference between healthy and diseased rhizosphere soil of P.notoginseng?P<0.05?.3.Effect of exogenous PAs on the growth of F.oxysporum results showed that individual PA could inhibited the F.oxysporum growth,among them,the strongest inhibitory was observed for ferulic acid,then for p-hydroxybenzoic acid,in addition,the inhibition effect was consistent with PAs concentrations.For the spore yields,when,the stronger inhibition effect was presented when the PAs concentration as low as 5?g/mL,and the p-hydroxybenzoic acid's inhibition rate?58.71%?was the highest compared with control.In contrast,the presence of PAs largely stimulated the production of fusaric acid?FA?.The role of PAs in the F.oxysporum growth was as a double-role sword.4.A.annua leaves water soluble extract effect the growth of the F.oxysporum results decleared that A.annua covered on the surface of P.notoginseng soil could inhibit the occurrence of root-rot disease of P.notoginseng with the preventive effect even up to 76.6%.The mycelium growth,spore yields,hypha dry weight and FA content significantly decreased in a dose dependent manner,and decreased by 1.8,4.17,5.8 and 29.5 times respectively compared with control when the concentration was 13.45 mg/mL.In addition,the content of FA in medium was found to be positively correlated with the injury level of plant,r²=0.9406.Conclusion:After the occurrence of root-rot,the quality of P.notoginseng declined,and the allelochemicals content reduced.PAs cuold inhibit the hypha growth and spore yields of F.oxysporum,but stimulated the production of FA.The water soluble extract from A.annuae leaf inhibited the growth of F.oxysporum,and its inhibition increased in a dose dependent manner.