BLAST DISEASE OF BLACK GLUTINOUS RICE GERMPLASMS UNDER INOCULATION AT SEEDING AND TILLERING STAGES

Abstract

Black rice is an alternative source of blast disease resistance and appropriate screening method is necessary to be proposed. The objectives were to 1) evaluate leaf blast disease of different black glutinous rice genotypes, and 2) determine correlations between disease symptoms at seedling and tillering stages. Leaf blast disease for 25 black glutinous rice genotypes and 3 check genotypes were observed at Khon Kaen University, Thailand in 2013 and 2014. HY 71, Niawdam Gs.no.21629, Khaokam Gs.no.88084, KKU-GL-BL-05-003, KKU-GL-BL-05- 004, KKU-GL-BL-06-010 and KKU-GL-BL-06-023 were high resistant genotypes across growth stages, times of evaluation and years. Seedling and tillering stages were significantly different for severity index. Correlation coefficients between severity indices at seeding and tillering stages in 2013 and 2014 for evaluation at 7 days after inoculation (DAI) were 0.34 (p<0.01) and 0.29 (p><0.01), respectively, and for evaluation at 14 DAI were 0.40 (p><0.01) and 0.41 (p><0.01), respectively. Correlation coefficients between severity indices evaluated at 7 and 14 DAI for growth stages and years varied from 0.34 to 0.50 (p><0.01). The results suggested that screening of leaf blast disease at only seedling stage was not enough to identify resistant genotypes.><0.01) and 0.29 (p<0.01), respectively, and for evaluation at 14 DAI were 0.40 (p<0.01) and 0.41> .01) and 0.41 (p<0.01), respectively. Correlation coefficients between severity indices evaluated at 7 and 14 DAI for growth stages and years varied from 0.34 to 0.50><0.01), respectively. Correlation coefficients between severity indices evaluated at 7 and 14 DAI for growth stages and years varied from 0.34 to 0.50 (p<0.01). The results suggested that screening of leaf blast disease at only seedling stage was not enough to identify resistant genotypes><0.01). The results suggested that screening of leaf blast disease at only seedling stage was not enough to identify resistant genotypes.