| The using excessive pesticides will lead to many problems,such as ecological imbalances,agricultural products quality declining,and pesticide residues in agricultural production.Meanwhile,with the improvement of the living level,people paid more and more attention to the environment and product quality.Some new effective measures and methods are urgently needed to replace chemical control.Biological control can control plant diseases by using microorganisms as biocontrol factors,the method has become an important mean to replace chemical control.Trichoderma spp.is a widely distributed species in the world.It has important functions within controlling crop diseases,promoting plant growth and soil remediation.In this study,Trichoderma GF-10 strains was isolated from the tobacco rhizosphere soil,meanwhile,its antagonistic mechanism and colonization were investigated.In addition to,we made water dispersing granules of the strain for more effective prevention and control the tobacco black shank.Our research contents are follows as:1)Identification of GF-10.In this study,a strain of GF-10,which has a good antagonistic effect on tobacco black shank,was selected from tobacco roots and identified by morphology and phylogenetics based on ITS,tef1α,and rpb2 genes.The results indicated the strain is Trichoderma citrinoviride.2)Biocontrol characteristics of GF-10.Antibacterial properties research:Through liquid fermentation test,the antibacterial rate of GF-10 strain against tobacco black shank reached94.49%;the dual culture experimental result showed that GF-10 can parasitize the tobacco black shank hyphae and cover its colony in space,meanwhile,it can produce much more spores on the colony.3)Investigation on soil colonization ability of GF-10 strain and affecting agronomic traits of tobacco.The investigation results showed that the GF-10 strain could stably colonize at the tobacco seedling stage,and the colonization amount reached 4.33×10~6cfu/g.In the field,the colonization ability of the strain decreased,and the colonization amount was 2.2×10~3cfu/g;the results also affected the promoting growth bility of the GF-10 in the field.4)Preparation of Trichoderma water-dispersible granules.In order to obtain a fungicide with convenient storage,strong colonization ability and good control effect,we developed the water-dispersible granule of GF-10.The carrier and auxiliaries of the water-dispersible granules were screened by single factor;then the PB experiment,the steepest climbing test and the central combination experiment were executed to obtain a carrier and auxiliaries with good compatibility with GF-10.The fungicide contained 0.74%sodium alginate,0.71%carboxy methyl cellulose,0.7%potassium dihydrogen phosphate,0.7%polyethylene glycol,0.35%?-cyclodextrin,0.35%sodium sulfate.The orthogonal design is used to test the process conditions(particle size,drying temperature,drying time)which affect the disintegration,suspension and wettability of the water-dispersible granules,and the processing technology of the water-dispersible granules is obtained under the condition.The drying time is 24h,the screening particle size is 0.4mm,the drying temperature is 30℃.Finally,the water dispersible granules meeting the national standard requirements are obtained.In this study,Trichoderma citrinoviride GF-10 with biocontrol potential was identified,its biocontrol mechnism and the colonization was studied in two stages of the seeding and the field,the results showed could produce antagonistic and nutritive competition on phytophthora nicotianae,meanwhile,the strain owns the growth-promoting affect on tobacoo seedling.Thus we studied the water dispersible granule of the strain,the agent can meet the national standard requirements for the production.The study is significant for understanding the antagonistic mechanism of Trichoderma citrinoviride GF-10,and promoting the commercial applying of the strain. |
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