Effects Of Calcium Oxide On Control Of Fusarium Wilt Of Watermelon And Its Preliminary Mechanism Research

In this study,five concentrations(0(CK),0.67(S1),1(S2),1.34(S3),1.67(S4)g/kg)of calcium oxide were used to evaluate the effects of calcium oxide on watermelon fusarium wilt by the dynamic changes of the soil physicochemical properties,the amount of fungal bacteria in Fusarium oxysporum f.sp.Niveum(Fon-1),the effects of disease control and plant growth.At the same time,the influence of calcium concentration on hypha growth and sporulation of specialized Fusarium oxysporum f.sp.niveum and the detection of soil microbial diversity by high throughput sequencing were studied on the preliminarily mechanism of prevention and control,so as to provide theoretical basis for watermelon fusarium wilt prevention.The results of the experiment are as follows:1.The application of calcium oxide in soil can effectively promote the growth of watermelon and inhibit the occurrence of watermelon fusarium wilt.When soil was applied with different concentrations calcium oxide,soil p H and EC values increased grads and 30 d tended to be stable.The incidence of watermelon wilt was significantly reduced,and the relative control effects of each treatment were 27.4%,36.9%,59.5% and 61.9% respectively.After planting 10 d,all treatments promoted the growth and development of plants and increased the water content of plant leaves.The effect of calcium oxide application on 1.34g/kg was the most significant.2.The application of calcium oxide in soil can effectively reduce the number of pathogenic bacteria and culturable fungi in soil,and increase the number of culturable bacteria and actinomycetes in soil.The number of soil pathogenic bacteria and the number of culturable microorganisms were detected.The results showed that the number of spores of Fusarium oxysporum in each treated soil showed a decreasing trend,which was significantly different from that of the control.The most obvious decrease of the spores of Fusarium oxysporum f.sp.niveum in 0~10 d decreased by 13.2%,32.1%,60.7%,82.8% and 89.2% respectively.The results of PDA plate bioassay showed that when the calcium concentration was higher than 80 mmol/L,the growth and sporulation of the pathogen began to be inhibited,and the inhibitory effect was strengthened with the increase of concentration.In addition,calcium oxide treatment can increase the number of bacteria and actinomycetes in the soil,and reduce the number of soil fungi.3.The application of calcium oxide in soil can increase soil bacterial diversity and reduce soil fungal microbial diversity.Through the high-throughput sequencing analysis of soil genomic extracts from pot experiments,the results showed that calcium oxide significantly increased soil bacterial shannon index and decreased shannon index of fungi.In addition,the microbial abundance of Flavisolibacter,Sphingomonas,Gemmatimonas,Opitutus,Devosia,Tomentella,Mortierella and Aspergillus was significantly negatively correlated with the incidence of fusarium wilt.And the microbial abundance of Mizugakiibacter,Rhodanobacter,Gemmatirosa,Crenotalea,Acidibacter,Dyella,Bryobacter,Fusarium,Chaetomium,Rhizopycnis and Monosporascus was positively correlated with the occurrence of fusarium wilt.