Integrative Laboratory and Field Evaluation of Landraces and Local Cultivars of Rice (Oryza sativa L.) For Drought Adaptability under the Western Undulating Zone of Odisha

Abstract

A diverse panel of 110 rice genotypes, comprising 56 landraces, 42 local cultivars, and 12 released varieties, was initially evaluated for streptomycin sensitivity using the bleaching index (BI) as a proxy indicator of stress adaptability. Based on BI responses, 22 genotypes exhibiting zero BI, 21 genotypes with BI of one, along with a drought-tolerant check, were selected for field evaluation, as lower BI values are indicative of greater adaptability and potential resilience to abiotic stress. A total of 44 rice genotypes were subsequently assessed for drought tolerance under normal (irrigated) and stressed (non-irrigated) conditions at the Regional Research and Technology Transfer Station (RRTTS), Bhawanipatna, under Odisha University of Agriculture and Technology, located in Kalahandi district of Odisha. The experiment was conducted over two consecutive seasons (2019–2020 and 2020–2021) to ensure the robustness and consistency of results. Across genotypes, moisture stress induced earlier flowering and maturity by 5–10 days compared to irrigated conditions. Drought stress significantly increased the number of chaffy spikelets (10–60 per panicle) and reduced 1000-grain weight by 0.5–10.0 g. However, select genotypes, including Karpurabas, Parbatjeera, Ganjam Local-2, Basumati, and Acharmati, exhibited an increase in grains per panicle under stress, suggesting compensatory yield mechanisms. Yield reduction under drought ranged from 6.9% to 67.8% among genotypes. Notably, Kalajeera, Karpurabas, Nua Acharmati, Nua Kalajeera, Acharmati, Barikunja, Ganjam Local-2, and Chatianaki recorded less than 20% yield reduction, reflecting superior drought adaptability. The significant association between low BI values and reduced yield loss under drought underscores the effectiveness of streptomycin-induced bleaching as a rapid preliminary screening tool. Integrating laboratory-based BI screening with multi-season field evaluation offers a pragmatic strategy for identifying resilient rice genetic resources to enhance drought tolerance and yield stability in upland rice ecosystems.