Screening of Rice (Oryza sativa L.) Genotypes for High Temperature Stress under Temperature Induction Response

Plants are exposed to multifarious external environmental conditions that affect plant growth, development and productivity. Heat stress is one of the abiotic stress that occurs due to high ambient temperature. Also, it is a serious threat to crop production worldwide. Rice is a major food crop cultivated all over the globe. In the present study, temperature induction response (TIR) was carried out for screening the rice genotypes. Initially, three rice genotypes namely Swarnamukhi, Kasalth and N22 (tolerant check) were used to standardize the optimum induction temperature and lethal temperature. Optimum induction temperature was 46-54o C and the lethal temperature 56oC were standardized for rice. At this temperature, a total of 58 diverse genotypes were screened for high-temperature stress tolerance. Among the genotypes tried, sivapu chithiraikar (94.33%), kavya (93.67%), kasalath(94.23), samleshwari (93.56), poongar (87.34), vedhividangan (75.10), Naveen (89.56), surakuruvai (84.90), swarnamukhi (92.10), vellaikatrai (80.50) and kavuni (92.60) expressed higher seedling survival percentage of tolerance (93.5%) to high temperature and remaining were identified as temperature susceptible as compared to control (100% survival). There was a considerable variation among the genotypes screened for acquired thermotolerance. Results suggested that TIR is a simple and powerful technique and can be used to screen a large population at the seedling stage to identify thermotolerant lines.