Antagonistic Bacteria to Inhibition Pathogenic Fungi in Rice

Abstract

This study aimed to investigate antifungal efficiency of antagonistic bacteria G5-5 in experimental fields. By spraying bacterial suspension 5 x 10⁸ cells/ml on 12 days - rice plant,              15 ml/plant. Then the plants were kept in dark room and covered with black plastic sheet for 24 hours. After that the plants were exposed to light for 12 hours then to dark for 12 hours. The light/dark cycle was conducted for 3-7 days. The results found that the relative disease severity of antifungal against Bipolaris oryzae showed significantly was 41%, which represented moderate susceptible level of inhibition. The biological control efficiency was 54.61%. The growth inhibition of Rhizoctonia solani were examined by spraying bacterial suspension 3 days before fungal inoculation. For fungal inoculation the 0.5 cm - radius agar wells were punched on PDA by cork borer. Then bacterial suspension was sprayed twice for 3 days interval. After 7 days of fungal inoculation, percentage of disease severity and diseased rice shoots were 14.16 and 100, respectively. The morphological study of antagonistic bacteria G5-5 found that the colony was white translucent, raised, undulated and greasy. Gram staining indicated that it was a gram positive rod with linear cell arrangement and endospore development. Therefore, it was classified to Bacillus sp.