Inhibition Effect Of Mustard Extract On Watermelon Fusarium Wilt And Its Effect On Microbial Diversity Of Watermelon Rhizosphere Soil

Watermelon is summer cool and refreshing good regular fruit,our country is watermelon production and consumption power,with the growing market demand,watermelon cultivation area increased year by year,followed by continuous cropping obstacle of the soil is more and more serious,light person production and the person that weigh,even how safe and effective prevention and control of watermelon fusarium wilt has become an urgent problem,also become the focus of many science and technology workers.Nowadays,there is an increasing demand for green,environmentally friendly and safe food in the society.It is of great scientific value and practical significance to extract bacteriostatic active substances from edible plants which have antibacterial effect and are harmless to human health.In this experiment,the melanin watermelon and local mustard shoots were used as experimental materials,and 5 concentrations of mustard extract were treated with 0mg·m L¹（CK）,6.25 mg·m L^-1,12.5 mg·m L^-1,25 mg·m L^-1,50 mg·m L^-1.To develop and replace chemical fungicides with botanical fungicides suitable for watermelon wilt,the main results are as follows:1.Within a certain concentration range,mustard extract treatment had a certain inhibitory effect on watermelon fusarium wilt bacteria,of which 12.5 mg·m L^-1treatment had a better effect,with a 13.33%reduction in incidence and a 12.5%reduction in disease index compared with CK.At the same time,mustard extract treatment promoted the growth amount of watermelon plants,and the plant height,stem thickness,dry mass and fresh mass were significantly improved compared with CK.The activities of SOD,POD,CAT and APX in watermelon leaves were increased by all concentrations of mustard extract,and the 12.5 mg·m L^-1treatment was better.The activities of SOD,POD and CAT were significantly increased by 12.61%,28.88%and 9.91%,respectively,compared with CK.The extract treatment also significantly reduced MDA content in watermelon leaves and increased H₂O₂content and soluble sugar content in plant leaves.In summary,a certain concentration of mustard extract can reduce the incidence of watermelon wilt,improve the ability of plants to resist adversity,and promote the growth of watermelon seedlings.2.As the concentration of mustard extract increased,the number of actinomycetes,the number of bacteria and the total number of bacteria in the watermelon rhizosphere soil all increased first and then decreased,while the number of fungi decreased significantly first and then increased slowly.When the concentration was 12.5 mg·m L^-1,the results were better.The number of actinomycetes increased by 48.14%,the number of bacteria increased by 17.15%,the number of fungi decreased by 32.54%,and the total number of bacteria increased by18.16%.Treatment with mustard extract could improve the activity of catalase,urease,sucrase,phosphatase and other enzymes in soil.When the concentration was12.5mg·m L^-1,the effect was better.Catalase activity increased by 53.96%,urease activity by 29.41%,sucrase activity by 5.4%,and phosphatase activity by 37.43%.In a certain concentration range,mustard extract treatment can also improve soil PH,reduce soil conductivity,increase the number of pseudomonas in watermelon rhizosphere soil,significantly reduce the number of fusarium oxysporum in rhizosphere soil.In summary,the treatment of mustard extract within a certain concentration range can improve the soil environment of watermelon rhizosphere,reduce the number of harmful bacteria,improve the soil enzyme activity,and promote the growth and development of watermelon plants.3.High-throughput sequencing technology was used to analyze the bacterial diversity of watermelon rhizosphere soil treated with mustard extract.The results showed that the mustard extract treatment increased the species abundance of soil bacteria in the early stage of colonization,but had no significant effect on bacterial species diversity.At the later stage of colonization,when the concentration was12.5mg·m L^-1,the mustard extract treatment increased the species abundance and species diversity of soil bacteria.On the genus level,a total of 237 bacterial genera were detected in 18 samples.On the 3rd day of colonization,when the concentration was 12.5mg·m L^-1l,the relative abundance of the Flavisolibacter,Pseudomonas,Bacillus and Terrimonas were significantly increased in the treatment group,and the relative abundance of Chujaibacter and Sphingomonas was significantly decreased in the treatment group.At the 23d of colonization,the abundance of Chujaibacter in the treatment group at a concentration of 12.5mg·m L^-1was significantly lower than that in the control group,and the relative abundance of other bacteria genera was significantly higher than that in the control group.When the concentration was25mg·m L^-1,the relative abundance of each dominant bacteria genera in the treatment group was significantly higher than that in the control group.In the 23d of colonization,most of the dominant bacterial phylum and genus were negatively correlated with the incidence of watermelon fusarium wilt,Terrimonas,Bacillus and Pseudomonas were significantly negatively correlated with the incidence of watermelon fusarium wilt,and the species abundance of Chujaibacter was positively correlated with the incidence of watermelon fusarium wilt.At the 23d of colonization,there were many bacteria genera with correlation with soil surface enzyme activity at the genus level,and urease activity was positively correlated with species abundance of Bacillus and Sphingomonas.There was a significant positive correlation between sucrase activity and the abundance of isolibacte species.The activity of acid phosphatase was positively correlated with the abundance of Bacillus and Pseudomonas.Catalase was positively correlated with the abundance of Terrimonas,Bacillus and Pseudomonas.4.High-throughput sequencing technology was used to analyze the effect of mustard extract treatment on the fungi diversity of watermelon rhizosphere soil.The results showed that the mustard extract treatment reduced the species abundance of soil fungi in the early stage of colonization,but had no significant effect on the fungus species diversity.At the late stage of colonization,mustard extract treatment reduced the species abundance and species diversity of soil fungi.The treatment of mustard extract changed the structure of soil fungus community in the early stage of colonization.At the 23d of colonization,the structure of the soil fungal community was significantly different between the treatment group and the control group,and the structure of the soil fungal community was also significantly different between the two treatment groups.Engraftment 3d 12.5mg·m L^-1mustard leaching solution treatment significantly reduced the Staphylotrichum,Archaeorhizomyces,Fusarium species abundance,significantly improved the Sagenomella,Thermomyces,Schizothecium,Mortierella species abundance.Engraftment in 23 d,mustard leaching solution treatment compared with controls significantly reduced Schizothecium,Fusarium,Thermomyces,Penicillium,Sagenomella,Archaeorhizomyces species abundance.In the 23d of colonization,the eight dominant fungi genera were positively correlated with the incidence of Fusarium,Penicillium and sagenomellae.In the 23d of colonization,the correlation analysis between the enzyme activity of the root soil and the species abundance of the dominant flora of soil fungi in this period showed that,at the genus level,most fungi were negatively correlated with the activities of urease,sucrase,acid phosphatase and catalase.