| Early blight and gray mold tomato diseases,as two important diseases in tomato cultivation,have an important impact on the yield and quality.Although chemical pesticides play an important role in the control of two diseases,the problems caused by unreasonable use of chemical pesticides such as residue,pathogen resistance,phytotoxicity and environmental pollution can not be neglected.Therefore,the development of new green and safe pesticides is imminent.Endophytic bacteria as an important microbial resource of the biological control of plant diseases,and some strains play a dual role both in disease prevention and plant growth promote.On the one hand it can be processed into biological pesticides for field disease control.On the other hand it can be processed into microbial fertilizer for soil-borne diseases prevention and control,soil microbial flora improvement and crop yield and quality improvement.It is of great significance to achieve the goal of "reducing drug" and "reducing weight" and alleviating the negative problems of chemical pesticides and fertilizers.So,the endophytic bacteria with much better antifungal activity and promote the plant growth was selected,and the antifungal activity,antifungal substance,colonization,growth-promoting,Formulation and field efficacy were also studied in our study.The all results as follows.1.Twenty-eight strain with antifungal activity against Allternana solani and Botrytis cinerea were selected out from 58 strains by the method of tablet confrontation.Then,strain ZSY-1,could colonized in tomato roots and rhizosphere soil and hads good field control effect,was selected by pot and field experiment.The number of strain ZSY-1 in tomato root was 1.46×106 cfu/g,after inoculated for 15 days.The filed control effect of B.cinerea of strain ZSY-1 were 80.33%in leaf and 75.10%in fruit,respectively.Strain ZSY-1 was identified as Bacillus velezensis by morphology,physiology and biochemistry,16S rRNA,gyrA and gyrB gene.2.The antifungal substance of B.velezensis ZSY-1 was inferred as lipopeptides by the analysis of acid-base stability,temperature stability,UV stability,discharge characteristics,droplet collapse characteristics and the method of ammonium sulfate precipitation and hydrochloric acid precipitation and methanol extraction.Then,the lipopeptides was purificated by medium pressure chromatography and HPLC and identified as surfaction(1008D)and iturin A(1042D and1056D).3.The VOCs of B.velezensis ZSY-1 of antifungal activity was studied by flat-to-buckle method.The VOCs had much better antifungal activity against A.solani,B.cinerea,V.maliy M.fructicola,.oxysporum f.sp.capsicum,S.sclerotiorum,F oxysporum f.sp.niveum and C.lindemuthianum,and the inhibition rate were 83.0%,92.1%,83.2%,80.9%,76.7%,68.1%,57.0%and 70.6%.The VOCs type was identified by SPME-GC-MS.The best extraction time and temperature were 40 min and 70 ?,respectively.Twenty-nine VOCs were detected and four VOCs(4-Chloro-3-methylphenol;2,4-Di-tert-butylphenol;Benzothiazole;2,5-Dimethylpyrazine)had more than 85%antifungal activity against A.solani and B.cinerea.4.The promote role of B.velezensis ZSY-1 was studied by seed germination and plot experiment.Strain ZSY-1 could significantly increase the germination potential of tomato seeds,when the bacterial suspension concentration was 1.0 × 107 cfu/mL and fermentation broth dilution was 100.In addition,strain ZSY-1 could promote plant height,stem diameter,leaf area,fresh weight,dry weight and root length,dry weight,fresh weight and SOD,POD and CAT activity of aboveground shoots of tomato seedlings.The strain ZSY-1 mechanisms of promoting growth were drought,salt tolerance and IAA production.5.Wettable powder preparation formula was optimized by single factor and orthogonal test.The best recipe was fermentation broth 70%,wheat bran 10%,8%CMC-Na,8%sodium lignosulphonate,3%diffusion agent MF,10%sodium tripolyphosphate,8%calcium lignosulphonate,4%opened flour BX,2%penetrant T,2%Silok-7110,2%Silok-2235 and added to 100%by wheat bran.The number of the wettable powder of strain ZSY-1 was about 2×108cfu/g.The wetting time and suspension rate were 41.35 s and 89.16%,respectively.The control effect of 300 times diluted solution against A.solani was 79.01%and the 500 times diluted solution against B.cinerea was 87.37%in vitro.6.The best dilution of wettable powder of stain ZSY-1 was 300 times in field by filed efficacy test.Compared with control(80.22%and 76.55%),the control effect of wettable powder of stain ZSY-1 was similar at the lower index of pre-illness condition,and the control effect were 77.76%and 74.68%.The control effects were less than 60%at pre-medication condition index larger area.So,the wettable powder of stain ZSY-1 had good preventive effect for B.cinerea. |
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