Study On The Development Of Biological Seed Coating Agent For Inducing Soybean Resistance Cyst Nematode And Gray Spot Disease And Its Biocontrol Mechanism

In order to achieve the control of soybean cyst nematode and soybean gray spot disease,the main target of prevention and control is to control the soybean cyst nematode and soybean by coating the soybean seed with the bio-control fermentation broth.Biocontrol strains of gray spot disease,and the high-efficiency strain Snef66 obtained by screening was combined with Sneb207 Bacillus megaterium and Sneb253 Streptomyces venezuelae obtained in the laboratory,and at the same time Adding auxiliaries to make a new multi-functional biological seed coating agent SN103,and verifying the field test,aiming at solving the prevention and control problems of soybean cyst nematode and soybean gray spot disease in a safe and effective way.On the basis of its high-efficiency control of soybean cyst nematode and soybean gray spot disease,systematic research on the taxonomic status,inducing substances and mechanism of effective strains was carried out.The main research results are as follows:1.Screening of biocontrol strains for inducing soybean resistance to cyst nematode and gray spotWith soybean cyst nematode and soybean gray spot pathogen as the target,the soybean seed was coated with 4600 strains of fermentation broth in the preliminary screening test of soybean,and 8 effective strains were obtained,including 6 fungi and bacteria.In the second year,the eight strains obtained from the initial screening were tested in greenhouse potting and field validation.The final screened Snef66 strain not only induced soybean anti-cytoplasmic disease and gray spot disease,but also promoted and increased yield.2.Identification of biocontrol strains that induce soybean resistance to cyst nematode and gray spot.Identification of effective bacterial strains: Two biocontrol bacteria were screened by morphological,physiological,biochemical and molecular biology methods.The identification results showed that the bacteria Sneb13 was Bacillus,Bacillus cereus;the bacteria Sneb16 was Serratia plymuthica.Identification of effective fungal strains: Based on traditional morphological identification methods,combined with modern molecular biology techniques,six selected biocontrol fungi were identified.The results showed that the fungus Snef L7 was Fusarium genus Fusarium oxysporum;the fungus Snef66 was Penicillium,Penicillium oxalicum;the three fungi Snef X1,Snef X4 and Snef X10 were Trichoderma fungi,respectively green woodTrichoderma viride,Trichoderma pesudokoningii,Trichoderma longipile;fungus Snef W31 is Aspergillus,Aspergillus flavus.High-performance liquid chromatography(HPLC)was used to detect the content of scopoletin in the strain.The results showed that scopoletin was contained in Penicillium oxalicum and its content was high.3.Development of a new biological seed coating agent against soybean cyst nematode and gray spot diseaseTwo strains resistant to soybean cyst nematode obtained by screening in the laboratory were screened and screened for Penicillium oxalicum Snef66,and the final compounding ratio was determined by nematode contact test to be Sneb207:Sneb253:Snef66=2 ×109:109:109 =2:1:1.Then,the compounded biological agent was added,and after adding an auxiliary agent,a series of laboratory tests and field tests were carried out to verify the stability of the control effect.Finally,it was named as SN103,and SN103 was not only for soybean cyst nematode and gray spot.Disease control effect is significant and has a certain promoting effect on soybean germination and seedlings.4.Study on soybean resistance to gray spot induced by scopoletin coated seeds.The fermentation broth of the biocontrol strain Snef66 Penicillium oxalicum obtained by screening was tested to contain scopoletin,and the content of scopoletin was higher than that of the control.Therefore,the soybean seed was directly coated with scopoletin,and the test was carried out by plate sputum,seed germination,growth promotion,potted planting resistance test,and the results showed that the scutellaria treated seeds significantly improved the resistance to soybean gray spot disease.Sex,and at the same time has the effect of promoting growth and increasing yield.