Identification and agro-morphological characterization of rice genotypes resistant to sheath blight

Abstract

Rice is the most widely consumed staple food for a large part of the world’s human population, especially in Asia. Sheath blight caused by Rhizoctonia solani, is one of the most serious diseases of rice. Research progress is limited due to non availability of absolute resistant sources to sheath blight in rice. A total of 1013 germplasm comprising of mutants, introgression lines from wild species, A, B, R lines, Tropical japonica accessions, land races from north eastern India, wild rice accessions of O. nivara and O. rufipogon and gall midge biotype differentials maintained at ICAR-IIRR were evaluated with artificial inoculation for resistance to sheath blight disease during 2012 under field conditions. The germplasm identified as resistant/moderately resistant were further tested both under glass house and field conditions in the subsequent years (2013 and 2014) and seasons (Both Kharif and Rabi). Based on three years of testing, seven genotypes such as SM 801 (N 22 mutant), 10–3 (Introgression line), Ngnololasha, Wazuhophek, Gumdhan and Phougak (land races from north east) and RP 2068-18-3-5 (gall midge biotype differential) were identified as moderately resistant to sheath blight. Agro-morphological characterization using 62 DUS descriptors for two years (2013 and 2014) revealed that disease resistance positively correlated with stem thickness and negatively with tiller number. No correlation was observed with traits like plant height and heading date with sheath blight resistance. Resistant genotypes with medium to semi dwarf stature should be used in breeding programmes in the development of sheath blight resistant cultivars.