Screening of rice genotypes against brown leaf spot (Bipolaris oryzae) (Breda de Haan) shoemaker, under field and laboratory conditions at Banke, Nepal

A field experiment was carried out to screen 60 rice genotypes against brown leaf spot disease caused by Bipolaris oryzae with Sabitri as a resistant check and Mansuli as a susceptible check at Banke, Nepal. The field experiment was laid out in a randomized completed block design, and the seed infection screening was done in a laboratory with a completely randomized design. The disease assessment was done by calculating disease severity, the area under the disease progress curve (AUDPC), and the seed infection rate. The disease severity and AUDPC significantly varied for the tested genotypes. Based on the AUDPC and disease severity values, this study observed that one genotype was moderately resistant, 11 were susceptible, and 48 were highly susceptible. From our experiment, rice genotypes were primarily susceptible rather than resistant; thus, for the next-generation breeding program for brown leaf spot-resistant genotypes, more landraces should be screened from diverse environments of Nepal.