Effects Of Artificial Nutrient Substrate On Root Knot Nematode And Fusarium Wilt Of Continuous Cropping Cucumber

The production of protected vegetable is mainly cucumber cultivation.However,with the gradually prominent contradiction between the demand for the scale and specialization of facilities production,the phenomenon of continuous cropping of cucumber gradually increased,which has become an important factor restricting the production of protected cucumber.Accumulation of pathogens is one of the most important causes of continuous cropping obstacle,Fusarium Wilt and nematode disease are two extremely important continuous cropping diseases,its high incidence and harmful degree has seriously affecting the yield and quality of crops.A large number of studies have shown that nutrient matrix cultivation can effectively solve the problem of vegetable continuous cropping obstacles.In this paper,1-19 Continuous Cropping Cucumber is used as the experimental object,two different treatments of soil culture and nutrient substrate cultivation were set up respectively.Through the impact of cucumber disease incidence,the impact on the accumulation of pathogenic substances,as well as the impact of pathogenic factors and disease resistance factors four aspects,to explorethe role and mechanism of artificial nutrient matrix in solving continuous cropping obstacle,and to provide technical support for solving the problem of continuous cropping obstacle in protected cucumber cultivation.The main results are as follows:1.The two cultivation methods showed different degree of continuous cropping obstacles.The incidence of the disease increased with the extension of cultivation years,the incidence of 1-5 crops was relatively low,the 7-17 crops showed a gradual upward trend,the highest incidence of the disease index of 17 stubble was reached to 60,and after 17 crops,it began to decline slowly.Compared with soil culture,the incidence rate of substrate culture was low,and the incidence was slow.The results showed that the nutrient medium could significantly delay the incidence of root knot nematode and Fusarium wilt.2.By measuring the number of Fusarium oxysporum and root knot nematode population density found its incidence rate was positively correlated with it,there are more Fusarium oxysporum and nematodes content in the soil and matrix with high incidence,and there are less in the soil and matrix with low incidence.The highest stubble soil cultivation,thirteenth stubble,the number of Fusarium was 5 times that of the first crop and reached to 50×103cfu g-1 dry soil.The content of two kinds of bacteria by substrate culture was lower than that of soil culture.3.1n continuous cropping and soil matrix,were detected in benzoic acid,p-hydroxybenzoic acid,ferulic acid and vanillin.Ferulic acid content was significantly higher than the other three species,vanillin has the lowest content and has little relation with continuous cropping years.The benzoic acid,benzoic acid and ferulic acid showed obvious correlation with continuous cropping,the accumulation of phenolic acids increased with the increase of continuous cropping,and it increased sharply between 9-17 successive crops.Compared with soil cultivation,the content of phenolic acid in substrate culture was less.4.The pH value of soil and substrate of Continuous Cropping Cucumber tended to be acidic with the increase of continuous cropping.The contents of organic matter,alkali hydrolyzable nitrogen,available nitrogen,total nitrogen,available phosphorus and total phosphorus decreased with the increase of successive cropping.The substrate culture was higher than that of soil cultivation,the bulk density and EC value increased with the increase of continuous cropping,the substrate is lower than the soil,and there was no obvious change in available potassium.5.With the increase of succession cropping,the urease,polyphenol oxidase and catalase in soil and matrix showed a trend of rising first and then decreasing,substrate cultivation is higher than soil cultivation.Sucrase decreased slowly,the phosphatase increased slightly,but the difference between the two cultivars was not significant.6.Soil sterilization can kill soil pathogens effectively,the mortality rate of soil nematodes reached 98%under 60 degree heat treatment,mortality of Fusarium oxysporum reached 86%,the incidence was 0,and the growth indexes of the plants were significantly higher than those of the non heated soil.In the application of nutrient substrate in continuous cropping of Cucumber,compared with the soil,the incidence of plant diseases and insect pests was obviously reduced,and the effect of delaying the occurrence of continuous cropping obstacles was shown,which can effectively delay the continuous cropping of 2-3 crops caused by root knot nematode and wilt disease.The results of this experiment can provide some technical guidance for field production.