Screening the potential of antagonistic microorganisms as biological control agent for controlling rice blast pathogen, pyricularia oryzae / Muhamad Syafiei Azali
One of the major diseases that attack rice is blast disease, which has caused a great economic loss in rice productions worldwide. This disease is caused by the fungal pathogen known as Pyricularia oryzae. Besides of yield reduction, this disease considered important due to the problem of fungicide...
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| Format: | Thesis |
| Language: | English |
| Published: |
2016
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| Subjects: | |
| Online Access: | https://ir.uitm.edu.my/id/eprint/99053/1/99053.pdf https://ir.uitm.edu.my/id/eprint/99053/ |
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| Summary: | One of the major diseases that attack rice is blast disease, which has caused a great economic loss in rice productions worldwide. This disease is caused by the fungal pathogen known as Pyricularia oryzae. Besides of yield reduction, this disease considered important due to the problem of fungicide resistance. Fungal pathogen P. oryzae has already developed resistance to several active ingredients of fungicide such as carbendazium and tricyclazole. In order to tackle the problem of fungicide resistance, reduce the application of fungicides in the rice fields is crucial needed. Biological control could be an alternative method for controlling blast disease of rice, which also could reduce the load of chemical fungicides on the rice field. In this study, bacteria and fungi were isolated from asymptomatic rice leaves and stem and were tested for their antagonistic potential against P. oryzae in vitro and in vivo. A dual culture test was conducted as primary screening to evaluate all isolated bacteria and fungi for their potential as biological control of blast disease. Out of 58 bacteria isolates, four isolates showed antagonistic activity against the pathogenic fungus in the dual culture test. Isolate named as B2 (Bacillus cereus) showed the highest percentage of inhibition of radial growth with value of 58.16% as compared to isolate B1 (Bacillus sp.), B3 (Bacillus sp.), and B4 (Bacillus sp.) which PIRG value of 25%, 44.71%, and 54.32% respectively. In culture filtrate test, isolate B2 also shown the highest suppressing effect against the growth of P. oryzae. Secondary metabolite produced by isolate B2 significantly inhibited the growth of the pathogen with 40.58% of PIRG value as compared to the control plate. In addition, a study of isolate B2 on four week old rice seedlings inoculated with P. oryzae also showed a low disease incidence (25%) and percentage of disease severity index as low as 12.5%. Out of 37 fungi that were isolated, none of them showed antagonistic effect against P. oryzae in the dual culture test. |
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