| Summary: | 碩士 === 國立中興大學 === 植物病理學系所 === 96 === Streptomyces saraceticus 31 and Streptomyces sp. 205 inhibited the growth of Phytophthora infestans, pif 65-1, Phytophthora infestans, pift 165-1, Fusarium oxysporium f. sp. cucumerinum, F.o.c. 100 and Monosporascus cannonballusr, MC-1 at dual culture test. SS31 and S205 reduced tomato late blight, fusarium wilt of cucumber, southern root-knot nematode and southern root-lesion nematode in greenhouse tests. Streptomyces sp. 233 could not reduce disease incidence, but produce higher quantity hydrolysed and free amino acid in soybean-sucrose cultural broth than the other two strains. These strains grew and sporulated very well on ISP2, ISP3, ISP4 and ISP5 medium. Scanning electron microscope results showed these strains had their own specific spores number on the spore chain and surface structure on the spores. In dual culture tests, the average inhibition zone of SS31 to pif 65-1, pift 165-1, F.o.c. 100, and MC-1 were 13 mm, 12.5 mm, 35 mm and 11 mm, respectively, S205 inhibition zone to these pathogens were 8 mm, 8 mm, 10 mm and 9 mm; S233 had no inhibitory effect to these pathogens. Only the day one soybean-sucrose broth culture filtrate of SS31 had antagonistic ability to tested fungi. The chitin cultural broth of SS31 and the soybean-sucrose cultural broth of all strains could reduce the hatching rate of southern root-knot nematode. The soybean-sucrose cultural broth of SS31 and S205 reduced the disease incidence and galling index. All cultural broth of three Streptomyces strains had inhibitory effect on southern root-lesion nematode, especially those with SS31. In greenhouse tests, all of three Streptomyces spp. could delay fusarium wilt of cucumber occurrence up to nine weeks, the disease incidence was 18.5% ~ 49.7% of the initial disease severity of control treatment. The soybean-sucrose cultural broth of SS31 and S205 could reduce the disease incidence on tomato late blight by post-treatment. The results of our research showed SS31 and S205 could control plant pathogenic fungi and plant parasitic nematode. Although S233 did not show control efficacy to these tested pathogens, it had the potent to be a biofertilizer for its high quantity of amino acid.
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