| Gray mold, which is induced by B.cinerea, has become the first of the three major diseases on tomato in some area. It can be harm to the growth of plants and the fruits during the storage and transportation. It seriously restricts the sustainable development of tomato production. Long-term use of chemicals not only make the resistant pathogens, significantly reduced the control effect, but also pollute environmental, harm to human health, destruction of ecology and sustainable development. Because of it has no these problems, biological control has get the favour of many scientists. In recent years it has been a large number of biological control examples with good outcome applying drip treatment. Based on many years research on biological control of our laboratory, this paper carried out the biological characteristics and the antagonistic capacity of 4 biocontrol strains(SC11, 153, F46 and SF6), then study the biocontrol efficacy against tomato gray mold and the influence on physiological reaction of tomato seedlings.The biological characteristic studies of four strains shown that they had obviously promotion on growth of tomato seedlings and colonization on tomato leaf blades, among them, Paecilomyces lilacinus 153 has the most significant promotion on the germination of tomato seeds, and it has the most obvious growth-promotion, and the colonization remain the maxium during the whole test time.The vitro antibacterical activity of the four strains were investigated. The results showed that all the four strains have siginificant inhibitition on B.cinerea. The antibacterical activity in dish of Streptomyces spectabilis SC11, and the inhibitition of its ferment filtrate on colonies expand and the mycelium dry weight of B.cinerea, and the control effects of its broth on lesion expand of vitro leavies and the tomato fruits showed the most obvious effects.While the ferment filtrate of SF6 has the most inhibitition on spores germination of B.cinerea.In the pot-study, the results showed that all the four strains have obvious biocontrol efficacy against gray mold on tomato seedlings, they can significantly reduce the disease index of gray mold, especially the PRE-treatments. As to the influence on the defensed-enzymes system, the four strains could markedly increase the activities of the defensed- enzymes and the content of Pro, while the content of MDA showed significant reduced.The results of the greenhouse study showed that the efficacy of 153 broth against gray mold on leaf blades and stems reached 49.13% and 61.34% respectively; while the efficacy of 10-diluted broth were 33.25% and 42.16% respectively.Meanwhile, we select the GFP gene to mark the improved biocontrol strain F1-35 and explore the expressing in it, then study the influence on physiological characteristics and the defense respones of watermelon seedlings, at the same time to explore the biocontrol effect against watermelon Fusarium wilt.The results of biological characteristic studies of F1-35 after marked showed that GFP gene stably present in the strain, and the gene doesn’t affect the spores yield and the GA of F1-35, it could colonized on/in the watermelon root and rhizosphere soil normally.Contemporary, the GFP gene doesn’t affect the biocontrol against watermelon Fusarium wilt, the biocontrol efficacy was as high as 60%;As to the influence on physiological characteristics and the defense respones of watermelon seedlings when coerced under Fusarium wilt, when control against the wilt, the strain F1-35 could improve the activities of defense system, especially some enzymes such as the activities of PPO, the biocontrol efficacy changes with the activities of PPO. |
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