Evaluation of Traditional Rice Varieties for Resistance to Rice Blast under Field Conditions

Abstract

Rice (Oryza sativa L.) is a staple crop worldwide but suffers heavy losses due to various diseases, with blast disease caused by Magnaporthe oryzae being the most destructive. Identifying durable resistance varieties is critical for sustainable rice cultivation. Traditional rice varieties (TRVs) adapted to diverse environments, harbour genes that can enhance resistance. The present study aimed to evaluate the resistance potential of 290 TRVs under field conditions. Phenotypic screening was carried out at AICRIP-ARS, Gangavathi, India, following the Uniform Blast Nursery (UBN) method. Artificial inoculation with a virulent M. oryzae isolate was conducted and disease reactions were scored using the Standard Evaluation System (SES). Among the accessions, 58 TRVs exhibited resistant reactions (scores 1-4), while 41 were moderately resistant (scores 5-6). The remaining 197 TRVs were highly susceptible, underscoring the intensity of pathogen diversity and conducive environmental factors in the hotspot region. None of the TRVs expressed complete immunity. The identification of resistant TRVs such as Bangara Sanna, Gowri Sanna, Udda Jyothi, Navali Saali, and several GP accessions highlights their potential as donor parents in breeding programs. Incorporating these resistant genotypes into molecular breeding, marker-assisted selection, and R-gene pyramiding strategies will be critical to achieving durable and broad-spectrum resistance, ensuring stable rice productivity under changing disease dynamics.