Cold stress resilience in rice: genotypic variation, yield traits, and GGE biplot insights

Rice (Oryza sativa L.), a staple food for over half of the global population, is highly sensitive to low temperatures, particularly during early growth stages, resulting in significant yield losses. Addressing cold stress during the early stages of rice cultivation by screening rice genotypes can ensure optimal crop establishment and subsequent growth. An experiment was carried out by selecting ten rice genotypes for evaluation for cold tolerance through laboratory-based germination assays followed by subsequent screening with respect to biometric and biochemical parameters. Meher exhibited the highest germination rate (95%) under cold stress conditions, while Jajati and Ranidhana showed minimal variation in germination (2-7%). PERCOL (Percentage of seeds with coleoptile superior to 5 mm) and REDCOL (Percentage of reduction in coleoptile length) values remained consistent for Jajati and Pradeep. Cold stress led to notable reductions in plant height (9.2-31.1%) and the number of productive tillers per plant (36.8-37.1%). Samanta and Birupa recorded the highest number of productive tillers under control and cold stress conditions, respectively. Panicle exsertion was marginally impacted in Ranidhana (2.9%) and substantial decline recorded in Meher (19.2%), highlighting genotype-specific resilience. Spikelet fertility and 100-seed weight declined by 5.2-7.2% and 15-18%, respectively, in Samanta, and Jajati. Seed yield per plant was highest in Birupa (12.25 g/plant) under cold stress conditions. GGE biplot analysis indicated Kharavela and Birupa as high yielders under control and cold stress, respectively. Highest proline (4.6 mg/g) and carbohydrate content (18.08%) were noted in Samanta. Ranidhana and Samanta resulted in stable yield across environments indicating broader adaptability.