Physiological Characterization of Heat Tolerant Hybrids in Rice (Oryza sativa L.)

摘要

A total of 83 genotypes consisting of 43 hybrids, four lines, 29 testers and seven checks were evaluated to identify heat tolerant hybrids, through physiological parameters such as chlorophyll fluorescence ratio, SPAD value, and membrane thermal stability. Regarding chlorophyll fluorescence (Fv/Fm) ratio at booting stage, the maximum values were observed in parental line CB00-13-55 (0.67) followed by HTL 31 (0.67) and COMS 24B (0.66). The hybrids which recorded followed by maximum (Fv/Fm) ratio were COMS 24A x CB00-13-79 (0.66) and COMS 24A x HTL 35 (0.66) followed by TNAU CMS 2A x CB00-14-56 (0.65) and COMS 24A x CB00-14-82 (0.65). At flowering stage, the chlorophyll fluorescence (Fv/Fm) ratio was maximum in the parental genotypes CB00-13-126 (0.66) and HTL 35 (0.66) followed by HTL 25 (0.66) and COMS 24B (0.65). The hybrids which recorded maximum (Fv/Fm) ratio were TNAU CMS 2A x CB00-14-56 (0.70) followed by TNAU CMS 2A x CB00-14-82 (0.67) and TNAU CMS 2A x IR 36 (0.66). Regarding thechlorophyll content, maximum SPAD value was observed in the parent CB00-13-79 (39.73) followed by CB00-13-97 (39.10) and HTL 39 (38.53) at booting stage. The hybrid which recorded maximum SPAD values were IR 68897A x CB00-13-52 (44.57) followed by COMS 24A x HTL 34 (43.83) and IR 68897A x CB00-13-104 (42.93). At flowering stage, the maximum SPAD values were recorded in the parental genotypes CB00-13-52 (44.67) followed by TNAU CMS 2B (41.80) and CB00-13-79 (39.63). The hybrid which recorded maximum SPAD values were IR 68897A x CB00-13-55(42.90) followed by TNAU CMS 2A x CB00-14-37 (41.77) and IR 68897A x CB00-13-52 (41.50). The results indicated that parents CB00-13-52, TNAU CMS 2B and CB00-13-79 and the hybrids IR 68897A x CB00-13-55, TNAU CMS 2A x CB00-14-37 and IR 68897A x CB00-13-52 have relative tolerance to high temperature. These hybrids may be recommended for cultivation under high temperature conditions.