| Summary: | 碩士 === 國立中興大學 === 植物病理學系所 === 107 === Numerous banana plant wastes, especially pseudostem (about 30.81%), have a significant impact on the environment after bananas are harvested. Reusing agricultural wastes to develop plant protection products could not only reduce waste pollution problems, but also promote the development of sustainable agriculture. The purpose of this study was to evaluate the effect of the extracts of banana pseudostem and microorganisms on the control of Pak-choi anthracnose disease caused by Colletotrichum higginsianum PA-01. The extracts of banana pseudostem were evaluated for its efficacy on the growth of Pak-choi combined with three kinds of inorganic salts. The results indicated that amendment of extracts of banana pseudostem with 3% (w/v) calcium oxide, 2% (w/v) potassium carbonate and 0.6% (w/v) sodium chloride named EBPmix was the best combination for the growth of Pak-choi. EBPmix at 100 and 500-fold dilutions could significantly enhance the growth of Pak-choi, cucumber, rice, and other test plants. After soil drenching with EBPmix, the number of yeasts increased by 2.2 times. In contrast, the populations of fungi such as Penicillium spp. and Aspergillus spp. were significantly reduced. However, although the amount of bacteria between treatment and non-treatment with EBPmix was not different, there were much more white color colonies of microflora than yellow colonies in the treated soil. Foliar spraying with EBPmix increased the amount of bacterial populations by 9.5 times. Forty-one bacterial isolates and twenty yeast isolates were obtained from soils and Pak-choi leaves treated with EBPmix. Five isolates, BEB-S01, BEB-L05, BEB-L06, BEB-L11 and BEB-L14, showed strong inhibitory effects on mycelial growth of C. higginsianum PA-01. The growth rates of BEB-S01, BEB-L05, BEB-L06 and BEB-L14 were enhanced when cultured in PNA medium with EBPmix and the inhibition ability to mycelial growth of the pathogen increased by 14-27 %. According to Biolog, 16S rDNA and 16S-23S rDNA internal transcribed spacer, BEB-S01, BEB-L05 and BEB-L06 were identified as a variety of Bacillus cereus group. Several recipes for culturing BEB-S01 were studied for inhibiting the pathogen. The results revealed that the fermented broth of BEB-S01 had stronger inhibitory effect on conidial germination and appressorial formation by 100 % inhibition when the nitrogen source in PNBE medium was replaced by casein. Then PCBE fermented broth of BEB-S01 amended with NaHCO3 could increase inhibitory effect. After this, the fermented broth of BEB-S01 amended with one of different plant oils was tested its inhibitory effect on C. higginsianum PA-01. The results indicated that the fermented broth amended with corn oil and clove oil at 50-fold dilution could reduce the conidial germination and appressorial formation of C. higginsianum from 68.3 % to 39.0 % and from 66.7 % to 16.0 %, respectively. In the greenhouse assay, spraying PCBE-S01C at 50-fold dilution to Pak-choi could reduce the disease severity of Pak-choi anthracnose from 62.5 % to 35.0 %. Furthermore, spraying PCBE-S01C to Pak-choi plants 24 hours before, simultaneously, or after inoculating with C. higginsianum PA-01 showed varying degrees of efficacy on controlling Pak-choi anthracnose. However, the result was more effective in reducing disease severity when spraying PCBE-S01C and inoculating the pathogen were at the same time.
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