Biological control of rice blast disease at seedling stage by bacterial antagonists
| dc.contributor.author | Karki, Laxman Singh | |
| dc.date.accessioned | 2016-01-14T06:33:17Z | |
| dc.date.available | 2016-01-14T06:33:17Z | |
| dc.date.issued | 1994-03 | |
| dc.description.abstract | Rice blast is a serious disease ~herever rice is grown. Effective control through resistant varieties and chemicals is avai I able but can be broken down because of the genetic versatility of the pathogen. Alternative control methods such as biological control would be a useful addition to existing measures. As such this study was i nit ia ted to assess the feasibility of biological control of rice blast in Malaysia. Rice foliage samples were collected from different locations in Kedah and Penang states. A total of 93 bacterial strains were i. sola ted from the samples. The bacterial strains were screened against the pathogen Pyr_icuJaria oryzae in vitro and in vivo. Non-pseudomonad strains RLO 34 and RLO 31 were found very effective in inhibiting the pathogen in agar plate tests. Preliminary in v_ivo tests. however, showed no correlation between disease SURpressive ability and in vitro performance of the isolates. In pot experiments, three strains RLP 17, HLP 5 and RLO 12 w~re found to have potential in suppressing disease severity. In a sihgle application, at the rate of 108 cfu/ml their individual disease score on a 1-9 scale was 4 with a pathogen concentration of lx105 spores/mi. Strains HLP 17. HLP 5 and RLO 12 were also screened in microplots under controlled conditions. The antagonists were applied three times, first as a seed t rea tmen t and sprayed twice. Disease control was more encouraging especially for RLP 17. The mean disease score of RLP 17, RLP 5 and RLO 12 was 2. 7, 5. 7 and 6. 0 respect ivelJy as compared to B. 2 for control plants. Identification of the three strains was performed. The strain RLP 17 was identified as Pseudomonas fluorescens, RLP 5 ·as P. aureofaciens and RLO 12 as P. cepacia. Studies to determine the mechanism of inhibition wet~e conducted in vitro and in vivo. From these preliminary studies iron regulated antibiotic p•·oduction was identified as the possible mechanism responsible for the pathogen inhibition, especially in the case of RLP 17 . | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/1611 | |
| dc.language.iso | en | en_US |
| dc.subject | Rice blast disease | en_US |
| dc.subject | Bacterial antagonists | en_US |
| dc.title | Biological control of rice blast disease at seedling stage by bacterial antagonists | en_US |
| dc.type | Thesis | en_US |
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