碩士 / 國立中興大學 / 植物病理學系所 / 101 / Fusarial wilt of watermlon is caused by soil-borne fungal Fusarium oxysporum (Schl.) f. sp. niveum (E. F. Smith) Snyder & Hansen, and it is hard to be controlled. Chemical fungicides and grafting bottle gourd (Lagenaria siceraria Ser.) are mainly used to control the disease in Taiwan. In order to search alternative methods, the purpose of this study is to use amendments and microorganism to develop a bioformulated cultural medium for controlling watermelon fusarial wilt. To compare different composition of spent forest mushroom compost (SFMC) mixed with Bas Van Burren No. 4 (BVB No.4) peat moss, it was found that the cultural medium consisted of SFMC and BVB No.4 at the ratio of 50：50 (v/v) was effective in reducing watermelon fusarial wilt, and made watermelon seedlings grown normally. The water-soluble extract of cultural medium SFMC50 amended with 0.75% shrimp and crab shell powder (SC75) or 0.25% blood meal (SB25) could reduce the conidial germination of F. oxysporum f. sp. niveum. The disease incidence of watermelon seedlings grown in cultural medium SC75 was reduced by 30.48%. Inhibition of conidial germination of the pathogen was nullified when cultural media SC75 and SB25 were steamed at 100℃ for 30 min. Eighteen bacterial isolates obtained from SFMC50 and SC75 were dually cultured with F. oxysporum f. sp. niveum on the potato nutrient agar plates. The results indicated that Bacillus subtilis Ju020 was able to inhibit the mycelial growth of F. oxysporum f. sp. niveum isolate FNH0103 up to 51.3%. The cultural medium SFMC50 amended with 0.75% (w/v) SCSP and antagonistic bacterium Ju020 (106 cfu/mL medium) (SCJ20) could reduce 40.3% of fusarial wilt on watermelon seedlings. The effect of cultural media SFMC50, SC75 and SCJ20 on the conidial germination of F. oxysporum f. sp. niveum was analyzed by slide agar-film culture method. The results showed that the conidial germination of F. oxysporum f. sp. niveum isolates FNH0103 and FNP0401 in the cultural medium SCJ20 were decreased by 37.33% and 36.67%, the length of conidial germ tube were reduced by 68.99±5.61 μm and104.65±1.85 μm, abnormal germ tubes were incited by 30.33% and 26.00%. The germ tube lysis percentage of F. oxysporum f. sp. niveum isolates FNH0103 and FNP0401 were observed by 45.67% and 44.00% 24hrs after treatment. Analyzed antifungal compounds in the cultural media by High pressure liquid chromatography (HPLC), it was found that the water-soluble extract of cultural medium SCJ20 had peaks similar to iturin A, but it didn’t have peaks similar to surfactin. The partial mechanisms for reducing fusarial wilt of watermelon seedlings with the cultural medium SCJ20 may attribute plenty of microbial activity and the antifungal activity of iturin A existed in the medium.
| Identifer | oai:union.ndltd.org:TW/101NCHU5363003 |
| Date | January 2013 |
| Creators | Wei-Shiou Chuang, 莊偉秀 |
| Contributors | 黃振文 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 59 |
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