Development And Field Effect Evaluation On Southern Blight Of JY-7-2L Biocontrol Fertilizer

Southern blight of Aconitum carmichaelii Debx caused by Sclerotium rolfsii is one of the soil-borne fungal diseases,which seriously restricts the development and economic benefits of industry of A.carmichaelii.Conventional chemical control is easy to cause pesticide residues,environmental pollution and other problems,and breeding of resistant varieties is progressing slowly.Therefore,there is an urgent need for a green,safe and efficient method to control southern blight.The research group preliminarily screened out the endophytic bacterium JY-7-2L of A.carmichaelii,which have strong ability to resist the pathogenic bacterium of white sericosis of aconitum through plate confrontation and aconitum section confrontation tests.In this study,based on previous work,antagonistic ability of strain JY-7-2L was verified in feild,and antagonistic mechanism of JY-7-2L against S.rolfsii was preliminarily explored.Nutrient carriers suitable for JY-7-2L were screened to produce biocontrol fertilizer and evaluate its effect in field application.The main results as follows:(1)JY-7-2L bacterial suspension was applied to the field to study its effect on control of southern blight.The result showed that JY-7-2L cell cultrue could significantly inhibit the occurrence of southern blight.In the tests conducted in Southwest University of Science and Technology and Qingchuan,Guangyuan,the biocontrol rates of JY-7-2L cell cultrue against the disease were 94.45% and 55.38%,respectively.(2)Plant culture was used to investigate the ability of JY-7-2L to secrete degrading enzyme and ferriferous carrier,as well as the effects of JY-7-2L cell-free fermentation filtrate and volatile gas on the growth of S.rolfsii.JY-7-2L can secrete antagonistic substances to inhibit the growth of S.rolfsii.JY-7-2L could produce cellulose degrading enzyme,glucan degrading enzyme and protein degrading enzyme.The cell-free cultrue filtrate of JY-7-2L could significantly inhibit S.rolfsii growth,sclerotium formation and germination of sclerotium,and the volatile compounds significantly repressed the hyphal growth of S.rolfsii.The presence of bac A,fen A,fen B,fen D,srf AA,and bae A genesby PCR amplification indicated that JY-7-2L was able to produce antifungal lipopeptides and polyketides.(3)Chicken manure compost,cow manure compost,oil cake and turf were used as carriers of JY-7-2L,the survival number of JY-7-2L in chicken manure compost was the highest,and the shelf life was the longest,so chicken manure compost was the most suitable carrier for JY-7-2L survival.(4)Biocontrol fertilizer was prepared by secondary solid fermentation of JY-7-2L and chicken manure compost and applied to field to evaluate the effect.The results of field experiment showed that JY-7-2L biocontrol fertilizer significantly reduced the incidence of southern blight and increased the biomass of A.carmichaelii.At 45 days,the biocontrol rate of JY-7-2L biocontrol fertilizer was 58.26%,and that of commercial Bacillus subtilis products was 21.74%.Compared with CK,JY-7-2L biocontrol fertilizer increased dry weight of stem,taproot and aconite by 105.03%,36.77% and 99.79%,respectively.Compared with commercial B.subtilis products,JY-7-2L biocontrol fertilizer increased the dry weight of stem,taproot and aconite by 48.02%,87.32% and 21.98%,respectively.In conclusion,strain JY-7-2L had high biocontrol potential against southern blight,and its biocontrol fertilizer could significantly inhibit the occurrence of southern blight and increase the biomass of A.carmichaelii.The experimental results can provide experience for the development of biocontrol fertilizer related to A.carmichaelii,theoretical and technical support for the green and sustainable development of A.carmichaelii planting.