| Tomato is one of the favorite vegetables in our country.Because of its rich nutritional content,unique taste and various methods,tomato is popular among people of all ages.However,with its continuous planting in greenhouses,tomato disease has become a key factor limiting tomato yield and quality,and Fusarium wilt is one of the most typical diseases,which is difficult to control and most common.For such soil-borne diseases that are common and difficult to control,the effects of common control methods are not very significant,including methods of improving agricultural practices,using physical methods,spraying chemical agents,etc..Bacillus biocontrol is a very important part of the biological control strategy because it can produce lipopeptide substances that inhibit pathogenic bacteria,can produce spores that can adapt to different growth environments,and have a variety of different modes of action.In this experiment,a strain of Bacillus amyloliquefaciens SDTB009,which has strong biocontrol activity against tomato Fusarium pathogen,was screened and isolated from the rhizosphere soil of healthy tomato plants.Through the activity identification,the identification of various physiological and biochemical indicators,and the molecules of the conservative motifs Identification,observation of its microscopic morphology using a transmission electron microscope,and its classification status became clear to the species.The bacteriostatic activity of fermentation broths with different concentrations of SDTB009 and the biocontrol effects of SDTB009 in the greenhouse and field were measured,and the control effects of SDTB009 combined with chemical agents were evaluated.At the same time,the lipopeptide material produced by SDTB009 was also isolated,purified,and identified,and its biological control mechanism for the prevention and control of tomato Fusarium was clarified.For the purpose of biological control,reducing the amount of target chemical agents and ensuring the sustainable development of the tomato industry,Provides a certain theoretical basis.The test results are summarized as follows:1.By observing the morphological growth of biocontrol bacteria SDTB009 in the plate,and determining the conserved motifs of 16S rDNA and gyrB and establishing the corresponding phylogenetic tree,SDTB009 was finally identified as Bacillus amyloliquefaciens.2.The indoor biocontrol effect test found that SDTB009 has a strong inhibitory effect on Fusarium oxysporum tomato specialization.The plate antisepsis results showed that the inhibitory diameter can reach 9-11 mm;the test proved that 10~8 CFU/mL of fermentation broth It has the strongest inhibitory effect on pathogenic bacteria.It has been found that SDTB009 has broad-spectrum antibacterial activity through indoor biocontrol activities of various pathogenic bacteria,laying a good foundation for the future development of SDTB009 as a biocontrol agent.3.The results of greenhouse pot test and field test show that SDTB009 fermentation broth can reduce the amount of difenoconazole in controlling tomato wilting,and can achieve similar control effects:SDTB009 fermentation broth and half the amount of difenoconazole The control effect of the difenoconazole preparation on tomato Fusarium wilt in the greenhouse was 78.13%,and the control effect of difenoconazole alone with a normal dose was 77.62%,and there was no significant difference in the control effects.The reduction effect of field application can reach 81.39%,while the control effect of difenoconazole alone is 80.91%,which is equivalent.4.Scanning electron microscope(SEM)observation found that SDTB009 strain can destroy the hypha structure of Fusarium oxysporum,distort and damage it,and limit its growth,thereby inhibiting the occurrence of disease.The TOF LC/MS was used to analyze and identify the bacteriostatic substances produced by SDTB009.The results showed that the fermentation broth of SDTB009 contained Surfactin,which may be its main biocontrol mechanism to prevent and control tomato Fusarium wilt. |
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