Isolation and Molecular Characterization of Rice Brown Spot Disease in Major Cauvery Delta Regions

Rice (Oryza sativa L.) is the second most important staple food among agricultural cereal crops, with over half of the world's population dependent on rice. 165.59 million hectares of land is used for rice production worldwide, yielding 518.1 million tonnes and a productivity of 4.68 t/ha (FAOSTAT 2022 - 2023). In India, the rice production is about 132 million tonnes which is produced in about 47 million hectares of land with a productivity of about 4.21 t/ha (Ministry of Agriculture & Farmers welfare, Government of India 2023). In Tamil Nadu, the rice production is about 6.8 million metric tonnes which is produced in about 2.21 million hectares of land with a productivity of about 3.76 t/ha (Department of Economics and Statistics, Government of Tamil Nadu 2022-23). One of the biotic stresses that accounts for about 15.6% of losses each year is rice disease. Of them, Bipolaris oryzae (Breda de haan) causing brown spots of rice is the most destructive disease which causes about 90% of yield loss. Ten isolates of brown spot pathogen were collected from the Cauvery delta regions and of them, the virulent isolate (Bo9) was characterized molecularly. All the isolates were studied based on their morphological characteristics. ITS primers were utilized to do the molecular characterization of the pathogen.