Biological control of Fusarium wilt of tomato by antagonistic bacteria
| Autor: | Lai, Yahn-Liang, 賴彥良 |
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| Rok vydání: | 1996 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 84 The purpose of this study is to detect the distribution of antagonists withinthe plant and to evaluate the effect of antagonists on control of Fusariumwilt of tomato after introducing antagonists into plant by thehypocotyl- cutting method. Nine isolates of Fusarium oxysporum f.sp.lycopersici (Fol) were collected from Chu Tze Hu, Hsinyi, and Kwantien inTaiwan. Among them, the isolate Fol-04 showed the highest virulence on tomatovareity Know-You 301 in pathogenicity test was used in this study. Based onthe results of evaluating the correlation between the inoculum density ofFol-04 and its disease index with root-prunning and soil infestation method,106 spores / ml and 105 propagules / g soil were selected as inoculumdensities for this study. According to analysis of the antagonistic ability of130 strains against Fol-04 isolates with dural-culture on PDA medium, 74strains expressed the inhibition distance ranging from 0.1~0.5 cm, 45 strainsfrom 0.5 to 1 cm and 11 strains greater than 1 cm. Thirty two strains showingthe inhibition distance greater than 0.7 cm were selected and introduced intotomato plants by the hypocotyl-cutting method to test for the ability ofcontrolling Fusarium wilt of tomato in greenhouse. The results revealed that 6out of 32 strains allowed the survival percentages of plants twice more thannon-treated control. Antagonistic bacterial strains 008, 082, and 085 whichshowed strong ability in disease- controlling were used for furthercharacterization, including their colonization within tomato plants andcontrolling ability. Strains 008 and 082 were Bacillus spp. and 085 strain wasPseudomonas sp. based on the Biolog identification system. The result ofevaluating antagonist populations within the tomato plants showed that thehighest population of these strains were detected in the lower half ofhypocotyl, and consequencely declined in the adventitious roots, the upperhalf of hypocotyl, and epicotyl. It was also found that strain 082 was thebest to spread upward from introducing site, followed by 008 and 085. Thepopulation dynamic of antagonists colonized on roots declined with the timeduring the period of plant growth. Fourteen weeks after introduced antagonistsinto plants, population of 008, 082,and 085 strain on roots remained to be4.1x103 cfu/g wet root, 1.89x104 cfu/g wet root, and 2.18x105 cfu/ g wet root,respectively. Based on the observations under T.E.M., these antagonistslocated in vascular tissues of hypocotyl 12 hours after introduction, and inthe cortex cells 28 days afer introduction. The yield of tomato was notinfluenced after these antagonists were introduced into the plant. Strain 008and 082 reduced significantly tomato Fusarium wilt after inoculation byroot-prunning method, while 085 showed no effectiveness. All theseantagonistic strains significantly reduced the tomato Fusarium wilt afterplants were transplanted in the infested soil. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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