Determination Change Rules Of Phenolic Acids In The Rhizosphere Soil Of Replanted Muskmelon And Degradation Of Trichoderma

Muskmelon(Cucumis sativus L.)is an important economic crop in Northeast china.In recent years,the continuous cropping obstacleshe of muskmelon have become increasingly prominent and serious diseases and insect pests with rapid development in Northeast China.One of the important reasons for crops to produce continuous cropping obstacles is muskmelon root exudates and plant residue decomposition.To investigate the allelochemicals of rhizosphere soil of muskmelon under different cropping years,pot experiments was conducted.The compounds in the soil were analyzed by high performance liquid chromatography(HPLC),screened for advantage of Trichoderma on degradation of phenolic acids from muskmelon soil to provide scientific basis for alleviating continuous cropping obstacle of muskmelon.1.To investigate the allelochemicals of rhizosphere soil of muskmelon under different cropping years,pot experiments was conducted.The compounds in the soil were analyzed by high performance liquid chromatography(HPLC).Seven phenolic compounds,p-hydroxybenzcic acid,vanillic acid,syringic acid,vanillin,coumaric acid,ferulic acid,benzoic acid were found in rhizosphere soil and the contents was increased with the increasing years of sole muskmelon cropping.And the total concentration of these phenolics reached 257.94 mg·kg-1 dry soil,which was significantly higher the control soil.With the increase of continuous cropping years of pot simulation,the Fusarium Wilt was occurred,the plant growth was inhibited,the fruit yield was significantly decreased,continuous cropping obstacle is becoming more and more serious.In addition,the soil samples were analyzed and identified of 18 regions in three provinces of Northeast China.The contents of 6 phenolic acids,such as benzoic acid and vanillic acid,were significantly different.2.Screening of Trichoderma species in continuous cropping soil of melon in Northeast China.The 124 samples of soil continuous cropping was collected in Northeast China,screening of Trichoderma strains were 66 strains,accounting for 53.23%of the total;the Trichoderma strains isolated in Heilongjiang area to 31 strains,strain quantity and isolation frequency higher than that of Jilin and Liaoning area.The strains of TQTH-03 and TSY-02 were screened by SA medium containing melon root exudates,which had good degradation effect on phenolic acids.3.The degradation system was established of phenolic acids in continuous cropping soil of muskmelon,and the degradation of phenolic acids in the continuous cropping soil of muskmelon was determined.By using high performance liquid chromatography to determination the degradation of phenolic acids in Muskmelon in rhizosphere soil by using exogenous spore suspension and PD suspension and wheat bran fermentation of Trichoderma,the results of the study show that Trichoderma can accumulate phenolic acids the effective degradation in soil,the wheat bran fermentation degradation rate can reach more than 25%,the most significant degradation effect;Two kinds of fermented liquid of degradation by using inorganic salt bacteria suspension and PD bacterial suspension,the results show that the degradation rate as high as 20%,the degradation is significant;By using inorganic salt spore suspension of Trichoderma to degradation mainly phenolic acids showed that the Trichoderma had good degradation effect,and the degradation ability was low when the concentration was high.4.Field experiments were conducted using Trichoderma and bio fertilizer as cultivation substrates to provide theoretical basis for solving the problems of continuous cropping of melon.The results showed that the incidence of muskmelon treated with Trichoderma was lower than that of CK,which was beneficial to enhancing the growth and disease resistance of muskmelon and alleviating the continuous cropping obstacle.