Screening for novel rice sheath blight resistant germplasm and their biochemical characterization

Rhizoctonia solani Kuhn causes sheath blight of rice which is a common and destructive disease. The present studies focus on screening of rice genotypes against R. solani to find out promising sheath blight resistant genotypes and the role of the defense-related biochemical enzymes in six different moderately resistance, moderately susceptible and susceptible germplasm lines. A total of 196 rice germplasm lines were used to conduct a field trial to screen sheath blight resistant germplasm during 2014–2015 and 2015–2016 crop seasons. The study identified 33.1% moderately resistant, 55.6% moderately susceptible and 11.2% susceptible genotypes to sheath blight in rice. Moderately resistant cultivar IC281785 recorded higher peroxidase activity (2.990) than moderately susceptible cultivar IC282450 (1.232). Higher PPO enzyme activity was observed in Tetep (1.729) followed by IC281785 (1.423) after 24 h of inoculation. Similarly, PAL activity was highest in moderately resistant cultivars than moderately susceptible and susceptible cultivars. The highest catalase activity was observed in moderately resistant cultivar Tetep (0.963) than susceptible cultivar PB1 (0.513) after 72 h of pathogen inoculation.