Identification and Genetic Divergence of Heat Tolerant Rice Genotypes

In Chhattisgarh, rice is also grown during summer season in about 2 lakh hectares, mainly in areas with canal irrigation. Usually the productivity during summer is higher than Kharif season. Rice is sensitive to high temperature stress at almost all the stages of its growth and development. High temperature (38°C) and humidity induces complete sterility, enhances foliage growth and impair biochemical yield. In this study, 40 different genotypes, including commonly grown varieties, were screened under field condition during December-January 2011 and 2012 during seedling stage at Research cum Instructional Farm, IGKV, Raipur (C.G.). The spikelet fertility is a more powerful indicator for evaluating the heat tolerance at the reproductive stage than other stages. Based on spikelet fertility percentage and yield of grain per plant genotypes ZAKHA (ACC 86841), N22 (ACC 4819), PEH-KUH-TSAO-TU (ACC 8237), N22 (ACC 117273) and IR 64196-3B-23-3 was observed good performance to high temperature. On the basis of cluster analysis 40 rice genotype for heat tolerance were grouped into 5 clusters. The highest numbers of genotypes were in cluster V. The highest inter cluster distance was in between cluster IV cluster I. The lowest inter cluster distance was found between cluster V and cluster I.