Isolation Of Endophytic Bacteria From Cucumber And Biocontrol To The Cucumber Grey Mold

Grey mold is a serious fungal disease frequently attacking vegetables in the protected fields. Traditional chemical control has caused serious residue and environmental pollution. Therefore, using microbial to control the disease is both safe and environment-friendly. In this research, we hope to get the antagonistic strain by screening the endophytic bacteria isolated from cucumber and study antagonistic reaction mechanism. The main results are as follows:One hundred and seventy-three strains of endophytic bacteria were isolated from various organs of cucumber. Strains isolated from root accounts for 42.8%, 32.4% isolated from leaves, and 24.8% from stem.The antagonistic screening of endophytes was carried out. Eight strains showed strong antagonistic activities to Botrytis cinerea by dual-culture tests. Fermentation filtrates of B12 and B13 which had significant inhibitory effects upon B. cinerea were screened out .Their inhibitory rates were 84.0% and 81.8%, respectively.On detached leaves of cucumber, fermentation filtrates of B12 and B13 had strong inhibitory effects to the pathogen. Their fermentation broth could strongly inhibit the spore germination of the pathogen, their germination rates were 5.5% and 8.6%, respectively.Inhibitory activities of fermentation filtrates were stable at high temperature (100℃), and at neutrality environment (pH 6.0-7.0).Strains B12 and B13 were able to colonize successfully in cucumber plants. After inoculating with their mutant strains, a number of labeled strains were found in different organs of cucumber plants in 25 days. Two strains showed effective control to cucumber grey mold in greenhouse. The preventive effects of their ferment broth were 70.5% and 68.7%, respectively. The therapy effects were 51.2% and 47.8%, respectively.