Screening of Germplasm Accessions for the Identification of Sources for Leaf and Neck Blast Disease Resistance in Rice

Abstract

Aims: Rice blast, caused by Pyricularia oryzae, is recognized as one of the most devastating fungal diseases affecting rice production worldwide. Consequently, resistance breeding demands sustained efforts to broaden the pool of blast-resistant rice germplasm for effective disease management. Therefore, sustained screening of rice germplasm for blast resistance is a key component of environmentally sound and durable disease management strategies. Place and Duration of Study: In this investigation, a subset 3K panel containing 200 accessions was selected and evaluated during Kharif 2024 at AHRS, Ponnampete, a well-known hotspot for blast disease, where natural infection occurs frequently. Methodology: Disease development was assessed for leaf blast in a uniform leaf blast nursery and neck blast in field conditions. Results: Disease scoring as per IRRI scale of 0–9 resulted in identification of the disease reactions ranging from highly resistant to highly susceptible. Significant variation in disease severity was observed among the accessions. Twenty-three accessions exhibited resistance to leaf blast disease, while 32 were classified as moderately resistant. Additionally, for neck blast, three showed strong resistance reaction, 29 were resistant and 37 were moderately resistant to neck blast. Importantly, IRGC 127835, IRGC 128105 and IRGC 125608 showed consistent resistance to both blast forms (immune to neck blast and resistance for leaf blast), indicating their suitability as promising donor lines for blast resistance improvement programs. Conclusion: The rice accessions identified as resistant can serve as promising donor sources for developing new disease-resistant varieties, contributing to rice improvement efforts in India as well as globally.