Studies On The Effect Of A Bacillus Amyloliquefaciens Ba168and Mechanism On Cotton Verticilium Wilt

Cotton Verticilium wilt, known as cancer in cotton planting, was currently one of themost serious soil-borne fungal diseases in cotton production, which restricted thedevelopment of the cotton industry. In order to obtain an efficient way to control the cottondisease, the Ba168strain, a Bacillus amyloliquefaciens that had been screened and selected byour lab, was selected to test whether it can make a difference. According to check the controlefficiency of Verticillium wilt, optimization of fermentation condition, colonization andgrowth-promoting action test, results about the principles of cotton verticillium wiltprevention were obtained as following:It had been proofed that Ba168can inhibit the growth of Verticillium dahiae Kleb bydish confrontation test. Pot experiments indicated that soaking cotton seeds by Ba168brothcould be used to control Verticillium wilt with higher control efficiency thanthiophanate-methyl WP. In other words, it was right and feasible to conduct the research touse Ba168to control cotton verticillium wilt.The optimum fermentation conditions of Ba168strain was initially identified asfollowing: medium (per1000mL): soluble starch37.5g, soybean extract30g,(NH4)2SO42g,MgSO40.2g, NaCl5g, K2HPO40.5g, initial pH7.5. Rotation speed180r/min, the incubationtemperature was30℃. At this point the fermentation broth Ba168cell concentration couldbe3.42×108CFU/mL.According to the screening of mutant and detection of colonization, it was concluded thatBa168had ability to colonize itself in soil. Most of Ba168survived in4cm depth under thesoil. What’s more, Ba168can colonize in cotton roots if a wound was available on surface ofcotton roots. It was uncertain that whether the strain Ba168could transfer itself from roots tothe up-ground tissue.Ba168fermentation broth could increase cotton heights, in which soaking treatment forheight increase was more effective. In addition, the strain Ba168can significantly improve thefresh weight of aerial parts and roots of cotton seedlings. Soaking seeds by Ba168broth couldsignificantly promote the growth of cotton seedlings above ground. Overall, thegrowth-promoting effect of Ba168strain on cotton was remarkable. Antagonistic activity of Ba168against Verticillium dahiae Kleb had been proved by dishtests, and studying on the colonization and growth-promoting effect of Ba168proved themany factors that acted a role in Verticillium wilt prevention. Because that there was hugedifference between the different mechanism of prevention methods, so it was difficult todevelop indicators to measure whether the right one or several specific role that accounted forthe major part. It is necessary to explore the interaction between bacteria and cotton foramplification of bio control effect.