Screening And Condition Optimization Of Biofumigation Cruciferae Materials For Soil-borne Diseases Of Tobacco

Soil-borne diseases are general designation of a kind of pathogens that live in or on the soil which infest soil plants and above-ground plants.Diseases are common in all major tobacco-producing areas in China,some fields are devastated,which seriously threatens the sustainable and healthy development of tobacco industry.Therefore,it is of great significance to find new prevention and control technologies for soil-borne diseases.Biofumigation is a soil-borne disease management method with broad development potential,it is environmentally friendly,no harmful surplusage,can effectively improve the physical and chemical properties of the soil and increase crop yield after fumigation.In order to screen Cruciferae biofumigation materials for soil-borne diseases of tobacco,combinations of laboratory experiment and pot experiment was used for tobacco black root rot,tobacco sickle root rot,and tobacco black shank.At the same time,the effect factors of fumigation were studied and the effects of biological fumigation on soil physical and chemical properties and enzyme activities were analyzed.The main results are as follows:(1)Five Brassica plants,including mustard(Brassica juncea(Linnaeus)Czern et Coss.),cauliflower(Brassica oleracea Linnaeus var.botrytis Linnaeus),Chinese cabbage(Brassica campestris L.ssp.chinensis(L.)Tsen et Lee),cabbage(Brassica oleracea Linnaeus var.capitata Linnaeus),oilseed rape(Brassica campestris L.ssp.Pekinensis)have inhibitory effects on three pathogens:tobacco black root rot(Thielaviopsis basicola(Brek.et Br.)Ferraris.),tobacco sickle rot(Fusarium solani(Mart.)Sacc.)and tobacco black shank(Phytophora parasitica var.Nicotianae).Among them,Erdaomei mustard has the best inhibitory effect on three pathogens,after 6 days of biofumigation treatment in the laboratory,the inhibition rates of the three pathogenic bacteria reached 87.87%,80.52%,82.89%.(2)Optimization experiment of biofumigation conditions for three pathogenic bacteria using Erdaomei mustard as biofumigation material,the results show that:in view of economic benefits,the optimal biofumigation addition of tobacco black rot is 2.0 kg/m~2,and the optimal field capacity is 70%;the optimum biofumigation addition of tobacco sickle rot is 2.0 kg/m~2,and the optimum field capacity is 70%;the optimum biofumigation addition of tobacco black shank is 3.0 kg/m~2,the optimum field capacity is 80%.It has a substantial inhibitory effect on three pathogenic bacteria when the temperature of biofumigation is maintained above 20°C,and biofumigation is more effective at temperatures above 30°C.Through research on the pathogenicity changes of tobacco soil-borne pathogens after biofumigation treatment show that the incidence of pathogens after biofumigation was reduced by 45%,55%,and 57%.(3)Experiments results on soil physical and chemical properties and soil enzyme activity show that biofumigation of brassica plants can increase the content of soil organic matter,total nitrogen,alkaline nitrogen,and available phosphorus,compared with CK,the increase amounts are 45.59%、18.28%、21.66%、26.20%.At the same time,it can increase soil urease and invertase,compared with CK,the increase amounts are 26.54%and 19.82%.(4)Pot experiment show that the biofumigation can effectively reduce the number of pathogenic bacteria in the soil,and prevent tobacco black root rot,black shank and sickle root rot,the control effects were 59.01%,62.83%,and 59.05%,which slightly lower than the chemical dazomet fumigation.