Abstract

Rice blast, caused by the fungal pathogen Pyricularia oryzae, is a major threat to rice production worldwide. As P. oryzae is a highly evolving and dynamic pathogen and adapting host plant resistance is the most significant way of managing the blast disease. The present study aims to assess the performance of rice genotypes across different locations to understand their adaptability and also to monitor the virulence patterns of the blast pathogen population. A multi-location trail was carried out with 39 cultivars consisting of near-isogenic lines, international differentials, donors and commercial cultivars possessing different genes for blast resistance by adopting Uniform Blast Nursery (UBN) at six locations in different agroclimatic zones of Andhra Pradesh and Telangana during Kharif 2023. There was significant variation in disease pressure among locations, with ARS, Nellore exhibiting the highest Location Severity Index (LSI) of 4.44 and ARS, Uttukur showing the lowest LSI of 2.76. The susceptibility Index (SI) 7.45 was recorded highest in the susceptible check (HR-12) while the resistant check Tetep showed the lowest SI of 2.16. Several genotypes carrying the Pi-1, Pi-12, Pi-z+Pi-a+Pi-i, Pi-54, Pi-9 and Pi-kh+ genes demonstrated consistent resistance across different locations. The study highlights the importance of considering gene combinations for durable resistance and the need for site-specific adaptation in rice breeding programs to combat rice blast effectively.