Rupinder KaurYashmeet Kaur2016-11-232016-11-232016http://krishikosh.egranth.ac.in/handle/1/87302Rice is very sensitive to high temperature especially at the reproductive and grain filling stage which leads to higher spikelet sterility and ultimately yield losses. The mean, maximum and minimum temperature in Punjab are showing an increasing trend over the last decade. The present investigation was, therefore, carried out with the objective to identify heat tolerant genetic resources for future genetic studies and breeding. A set of 100 Oryza sativa genotypes were screened for heat tolerance in two environments E1 and E2 in the field during kharif 2014. Data were recorded on various morphological characters i.e. days to 50% flowering, panicle exsertion, SPAD reading, flag leaf temperature, panicle temperature, spikelet fertility, 1000 grain weight, grain yield per plant and head rice recovery. Based on spikelet fertility, grain yield per plant, SPAD and 1000 grain weight, genotypes TD 25, Binulawan, Chiem Chanh, Teqing, Ai Lan Ke 1110,Hasan Serai, Jamajigi, CT 6510-24-1-2, UPL RI-7, Karayal, Tsipala Fotsy and Zao Shou 691-11 in environment E1 and genotypes BR 24, Binulawan, Chang Ch'sang Hsu Tao, Chiem Chanh, O-Luen-Cheung, Teqing, Ai Lan Ke 1110, Deng Deng Qi, Ea Houm, IR 77298-14-1-2, Hasan Serai, Jamajigi, CT 6510-24-1-2 and UPL RI-7 in environment E2 were relatively heat tolerant as they had high spikelet fertility and grain yield per plant under high temperature conditions. Some genotypes like IR 64-21, RTS 14, Chang Ch'sang Hsu Tao, Deng Deng Qi, Hong Mi Dong Mao Zhan and Lua Tau Duc in environment E1 and genotypes IR 64-21, Sanhuangzhan No 2, IR 36, Deng Deng Qi, E 5168, Hong Mi Dong Mao Zhan, Lua Tau Duc, Race, Tsipala Fotsy and Way Rarem in E2 were moderately tolerant as they had high spikelet fertility but average or slightly below average grain yield per plant. Grain yield per plant and spikelet fertility showed significant negative correlation with flag leaf temperature as well as panicle temperature. Genetic diversity was assessed between these genotypes using 48 SSR primers. The genotypes were grouped into three distinct clusters I, II and III based on genetic diversity. The desirable genotypes for various heat tolerant traits identified in experiment I were scattered in all clusters. The heat tolerant lines identified in this study could be used as donors in breeding programmes focusing on heat tolerance.Thesis