| Summary: | 碩士 === 國立虎尾科技大學 === 生物科技系碩士在職專班 === 107 === In order to cope with the possible shortage of food caused by the increase in population, all countries in the world are working hard to increase food production. However, how to achieve a balance between food production and environmental and ecological systems is the goal of national agricultural policy efforts, such as promoting organic agriculture is one of its policies. Biological control is recognized as one of the important means to replace or reduce chemical pesticide use in the future. Therefore, this thesis is conducted to isolate antagonistic microorganisms from organic tea garden and test their disease control ability, in order to develop bio-pesticide in the future.
The experimental fields were selected in the Fenghuang Nature Education Areas of the Experimental Forest National Taiwan University to explore the differences in the composition of soil microbial phase structure in tea gardens under the management of organic farming methods and conventional farming methods, and to screen for beneficial microorganisms from their soils and to detect anthracnose disease control of chinese cabbage caused by Colletotrichum higginsianum and the pathogen growth. According to soil microbial survey, the average number of fungi in organic tea gardens (59.82×103 cfu/g) is generally higher than that of conventional tea gardens (18.86×10^3 cfu/g); similarly, the average number of Trichoderma spp. is in organic tea gardens (23.72×10^3 cfu/g) is also about 4 times higher than the conventional tea garden (5.78×10^3 cfu/g). For bacteria and actinomycetes number investigations, the results showed no significant difference between organic tea gardens and conventional tea gardens. Comparing the number of microbial populations with the annual rainfall and temperature, it was found that the number of fungi and actinomycetes was positively correlated with the amount of rainfall in the area, but the number of all microorganisms was not significantly correlated with temperature. For dual culture of pathogen and antagonists on medium, 8 strains of Trichoderma spp. which had better growth inhibition of C. higginsianum were screened out, and to control anthracnose disease of chinese cabbage was detected in the greenhouse. The results showed that the 8 selected strains of antagonists were effective to reduce the anthracnose disease of chinese cabbage about 32~53% compared with the untreated control, among which strain O1-5-3 was the best. This strain O1-5-3 was identified by gene sequencing and assigned as Trichoderma virens.
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