| Tomato is an important vegetable crop in China,which was of vital importance to the development of modern agriculture and national economy.With planting years increasing,continuous cropping obstacle caused by Fusarium has became the main bottleneck of tomato cultivation.The main control method is high temperature shed with chemical pesticides nowadays.The control effect is unsatisfactory,continuous cropping obstacle is still serious.At the same time,high-dose chemical pesticide treatment caused a series of problems.The fundamental way to solve this problem is to establish a biological control technology system.From 2008 onwards,Institute of Plant Protection at Jiangsu Academy of Agricultural Sciences were working for biocontrol bacterial.After several years work,a high antagonistic strain B1619 was screened out employing tomato Fusarium oxysporum as an indicating strain.Bacteria B1619 has a strong inhibitory effect on Fusarium oxysporum.In order to further study the characteristics,induced disease resistance and using technologies of B1619.The following researches are included in this paper:1.Biological characteristics were studied in respects of metabolite species,biofilm morphology,temperature,pH,carbon nitrogen sources,trace elements,inorganic salt and growth curve.Results showed B1619 can produce protease,cellulose and iron,it also can form a dense and thick biofilm,at the same time,27 ?,pH 5.9,mannitol,beef extract,Ala,CaCl2 and MgSO4 were optimum for its growth.Logarithmic growth was at the first 24 hours,the cell number reach maximum at 24 h and its growth keep stable after 24 hours,it mainly keeps thalli before 24 hours while producing spores after 24 hours,the spore number reach maximm at 72 hours and its sporulation rate was high,even over 90%.In addition,we observe the cell morphology changes of B1619 at 24h,48h and 72h by scanning electron microscopy.2.To explore the potential mechanism underlying the induced resistance mediated by B1619,the expression profile of several plant defense-related enzymes,peroxidase(POD),superoxide dismutase(SOD),phenylalanine ammonia-lyase(PAL)and secondary metabolite malondialdehyde(MDA),several enzymes synthesis-related genes,SOD,POD1 and defense-related gene PR-1 a were monitored in different groups treated with B1619 or Fusarium oxysporum.Levels of SOD,POD,PAL activities and SOD,PODl,PR-1a were all significantly higher as compared with the control.At the same time,the level of MDA was lower than the control.The enhanced expression patterns of the above suggested that the induced resistance in tomato by B1619 might account for its ability to provide effective protection for tomato from wilt caused by the fungal pathogen Fusarium oxysporum.3.The experiments of pot experiment and dilute plate method were used to clarify the root colonization ability of B1619.The appropriate dosage and usage of B1619 were tested in this article.On this basis,Field efficacy trials and demonstration trials were conducted.The results showed that B1619 had excellent colonization ability around tomato roots.The amounts of B1619 was up to 5.9 ×104 cfu/g soil until the 21 days after seeding.The results also indicated that the control efficacy was better when B1619 was sprayed through root-drenching method or hole fertilization than other ways.6g per plant or above was the better doses.According to the field efficacy trials,the control efficacy of B1619 was about 65.1%?85.2%,which was significantly higher than the chlorolthalonil(75%)treatment.The demonstration trials indicated that the control efficacy of B1619 was up to 85%?90%. |
PDF Full Text Request