A preliminary screening of rice germplasms for reproductive-stage drought resistance: With selected traditional, improved, and exotic rice varieties at the Rice Research and Development Institute, Batalagoda, Sri Lanka

The rice plant is highly susceptible to drought stress at the flowering stage, which often leads to pollen and spikelet sterility and ultimately significant yield losses. As rice is the staple food of Sri Lanka, improving drought resilience is essential for ensuring food security. This study evaluated eight rice cultivars for growth and yield-related traits under drought stress at the reproductive stage to identify drought-resistant cultivars and effective screening traits. Field experiments were conducted under both drought and well-watered conditions in a randomized complete block design with three replications at the Rice Research and Development Institute (RRDI), Batalagoda, during the Yala 2023 season. Drought stress was imposed using a 20-day rainout shelter treatment at panicle initiation. Niyan Wee, Podi Niyan Wee, Azucena, and Black Gora maintained high shoot and root dry weights under both treatments. Yield reductions under drought ranged from 10% in Niyan Wee to 67% in IR64. Niyan Wee and Podi Niyan Wee were the least affected cultivars, maintaining a high number of panicles per hill, seeds per panicle, grain filling percentage, and grain weight. Azucena, Bg377, and Black Gora also showed lower yield reductions, whereas the known drought-susceptible cultivars IR64 and Bg352 were the most affected. Among the measured traits, the number of panicles per hill and the number of seeds per panicle showed a strong positive correlation with grain yield, making them reliable selection criteria for drought resistance. Overall, Niyan Wee, Podi Niyan Wee, Azucena, and Bg377 emerged as promising candidates for further drought-resistance screening and breeding programs.