Alleviating Of Muskmelon Soil Of Continuous Cropping Obstacles By Rotation And Biological Agents

Muskmelon(Cucumis sativus L.)is one of the most important economic crops in China,and it is an inappropriate continuous crop.In recent years,continuous cropping obstacles in muskmelons have become increasingly severe due to changes in cultivation patterns.The main cause of continuous cropping obstacles in muskmelons is the long-term accumulation of autotoxic substances secreted by the roots in the soil,altering the microbial flora of the soil,and thus causing autotoxicity and blight.In this paper,high performance liquid chromatography(HPLC)technology was used to detect different types of phenolic acids in rhizosphere soil of muskmelons and their effects on the soil microflora.It is aimed at screening out the best solution to overcome the continuous cropping obstacle of muskmelon.The main results are described as follow:1.The effect of soil treatment agents on phenolic acid contents and microbial communities in rhizospere soil of muskmelonUnder pot assay conditions,high performance liquid chromatography(HPLC)was used to determinate the content of phenolic acids in the rhizosphere soil of muskmelons was measured after using humic acid fertilizer,bio-fertilizer,soil continuous obstacle repair agent and fungicides.The results showed that compared with the controls,the phenolic acid content in rhizosphere soil of all treated muskmelons was decreased,and with the use of soil continuous cropping obstacles remediation agent and fungicides had the best treatment effect,which reduced 12.14% and 12.31% respectively.Illumina MiSeq pyrosequencing was also used in this research.We studied the biomass and diversity of fungi and bacteria in rhizosphere soil of muskmelon treated with humic acid fertilizer,bio-fertilizer,soil continuous obstacle repair agent and fungicides,that defined the effect of different soil treatment agent on rhizosphere microbial community.The results indicated that compared with the controls,the community richness and biodiversity of fungi were reduced,and the community richness and biodiversity of bacteria were increased in all treatments,what's more,it is the best effects with soil continuous obstacle repair agent and fungicides treatment rhizospere soil of muskmelon,and Proteobacteria and Ascomycota were predominant in all treatments.2.The effect of Trichodera spp.and bacterial manure on alleviating continous cropping obstacle of muskmelonIn this test,the HPLC method was used to separate and determine the variety and content of phenolic acids in rhizosphere soil of Trichoderma,Trichoderma+bio-fertilizer and bio-fertilizer.The results indicated that the phenolic acid content in rhizosphere soil of muskmelon showed significantly decreased after the application of Trichoderma and Trichoderma+bio-fertilizer,indicating that Trichoderma had good degradation of phenolic acids in soil.The phenolic acid contenting in the rhizosphere soil of the biofertilizer individual was higher than that in the control treatments,that because of the higher content of coumaric acid in the rhizosphere soil of muskmelon after the application of bio-fertilizer individual.Furthermore,the plant height of the three treated melon plants was significantly higher than the controls,and the morbidity was significantly lower than the control groups.This indicated that Trichoderma and bio-fertilizer had good effects on promoting the growth of plants and strengthening the resistance of plants,and the effect of applying Trichoderma spp.individual showed the highest significant.3.The effect of crop rotation on alleviating continous cropping obstacle of muskmelonThe HPLC was used to isolate and identificate the phenolic acids in rhizosphere soils of muskmelon with fennel,rape and onion after rotation,also 9 phenolic acids were detected,such as gallic acid,p-hydroxybenzoic acid,vanillic acid,syringic acid,vanillin,coumaric acid,ferulic acid,benzoic acid and cinnamic acid.The results showed that rotation of muskmelon and three crops all reduced the content of phenolic acids in rhizosphere soil.Among them,muskmelon/animal rotation reduced the content of total phenolic acids in rhizosphere soil by 47.5%,and the content of total phenolic acids in muskmelon/rape rotation decreased by 28.5%,muskmelon/onion rotation rhizosphere soil total phenolic acid content decreased by 58.7%.