Genetic Analysis of Key Traits for Sheath Blight Resistance and Yield Improvement in Rice (Oryza sativa)

Abstract

Rice (Oryza sativa) is a staple crop for more than half of the global population, with significant production in India. However, rice production suffers yield losses of 25-30% due to diseases, particularly sheath blight (ShB), caused by Rhizoctonia solani. This study evaluated genetic variability, heritability, and genetic advance in ShB resistance and yield-related traits in 360 recombinant inbred lines (RILs) across two seasons (dry season of 2022-23 and wet season of 2023) at ICAR-IIRR, Hyderabad. Traits such as plant height, lesion height, relative lesion height, and panicle number showed high heritability (>80%) and genetic advance (>30%), indicating their strong genetic influence and responsiveness to selection. These traits, especially relative lesion height, were identified as key indicators for breeding ShB resistance. In contrast, grain yield under inoculated conditions showed lower heritability, reflecting environmental effects and suggesting that indirect selection through stable, heritable traits may be more effective. This research offers a foundation for breeding high-yielding, disease-resistant rice cultivars, advancing sustainability in ShB-prone regions by maintaining stable yields even under pathogen pressure.