Screening of Trichoderma isolates as a biocontrol agent to control rice seedling diseases
| Autor: | Ting-Yu Chu, 褚庭語 |
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| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Rice is the most important staple crop in Asia. Rice seedling diseases caused primarily by seed-borne and soil-borne fungi, among which Fusarium fujikuroi, Pythium spp. and Athelia rolfsii, are the major causal agents. Substantial amount of fungicides is required to control these seedling diseases. The aim of this study was to seek biocontrol agents to replace fungicides in the protection of rice seedlings from diseases. Members of Trichoderma have been known to possess multiple mechanisms in inhibiting plant diseases, and are considered to be promising for the application in the rice nursery. Sixteen isolates of Trichoderma have been obtained. In additional to antagonistic test against Fusarium fujikuroi, Pythium arrhenomanes and Athelia rolfsii in plates, these 16 isolates were characterized in vitro by the productivity of antagonistic volatile and non-volatile compounds, hydrogen cyanide and siderophores, by the plant growth promotion capabilities via IAA production and phosphate solubilization, and by the parasitism via chitinase and cellulase production. These 16 isolates were also tested in vivo for their ability in controlling seedling diseases and promoting growth of rice seedlings. By analyzing studies between in vitro and in vivo, a standardized criterion for screening potential Trichoderma isolates based on in vitro experiments has been established. Isolates of Trichoderma meet the criteria are most likely to efficiently control rice seedling diseases caused by these three pathogens. The standardized criteria are as follow: Bell’s scales lower than 5 in dual culture against A. rolfsii, inhibition against F. fujikuroi by non-volatile compounds with inhibition rate of mycelium higher than 36%, production of chitinase and hydrogen cyanide. Five isolates met the standardized criteria. Furthermore, two of these five isolates which were significant in controlling diseases and increasing rice biomass were selected and used in the test of rice nursery box. These standardized criteria can be used to quickly screen large amount of Trichoderma isolates to obtaine more candidate isolates for further application tests. In conclusion to this study, the control of rice seedling diseases by Trichoderma isolates is promising. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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