Screening Rice Genotypes for Brown Spot Disease Resistance

A field experiment was conducted to screen 20 rice genotypes against brown spot disease caused by Bipolaris oryzae under natural epiphytotic field conditions at Bangaun, Dang, Nepal, from June 2018 to March 2019. The experiment was carried out in a randomized complete block design with 3 replications. Sawa Mansuli was taken as susceptible check and Sabitri as a resistant check in the experiment. Disease assessment was done by calculating disease severity and Area Under the Disease Progress Curve (AUDPC). Among the evaluated genotypes, disease severity and AUDPC varied in the field experiments. Rice genotypes showed the resistance to highly susceptible reactions based on AUDPC value which ranged from 88.51 to 260.65. Among the evalauted rice genotypes in the field experiment, the highest mean AUDPC value was recorded with Basmati (260.65) followed by Radha-13 (172.80) and the lowest was recorded with Kathe Jhinuwa (88.51). Similarly, the highest severity rate was recorded with Basmati (25.91) followed by Radha-13 (21.00) and Tilki (20.75) and the lowest was recorded with Kathe Jhinuwa (11.03) which was at par with Radha-4 (11.11) followed by Sukhadhan-1 (12.02) and Sabitri (12.06). The highest grain yield was recorded with Sarju-52 (4.32 t/ha) followed by Sabitri (4.19 t/ha). Grain yield was negatively correlated with mean AUDPC by 14.77%. Kathe Jhinuwa, Radha-4, and Sabitri can be used for higher grain yield purposes under similar field conditions and also can be utilized as the source of resistance in a plant breeding program.