Global warming predicted to affect food security, especially rice, which is stable food crop as it is vulnerable to high temperature. In the present study, a novel temperature induction response (TIR) technique was adapted for identifying highly thermotolerant rice genotypes. This approach of TIR involves, first the identification of challenging temperature and induction temperature and later standardizing them before being used for screening the material for intrinsic stress tolerance. A lethal temperature of 55°C for 2 hours and induction treatment from 36°C-52°C for 5 hours was standardized in the laboratory. Using this standardized TIR protocol, highly thermotolerant rice genotypes were screened from 72 rice germplasm. Sufficient genotypic variability was noticed from zero level to 100% level of tolerance. Among the genotypes, NLR-145 showed highest thermotolerance in terms of 100 per cent seedlings survival and no reduction in root and shoot growth. NLR-40066, NLR-40070 and NLR-40050 also showed higher thermotolerance in terms of 90% seedlings survival and no reduction in root and shoot growth. This study revealed that TIR technique can be used for identification of thermotolerant rice genotypes. The identified rice varieties can be used as donor source for developing high temperature tolerant rice genotypes to withstand future temperature rise.
Lethal temperature, temperature induction response, thermo tolerance
