GENETIC ANALYSIS OF VARIOUS AGRO-MORPHOLOGICAL TRAITS IN RICE (Oryza sativa L.) USING CMS SYSTEM UNDER TEMPERATE CONDITIONS Waseem Hussain* and Gulzar S Sanghera Mountain Research Centre for Field Crops, SKUAST-K, Khudwani, Anantnag, 192102 Kashmir, India Email id: wasimmadni29@gmail.com Rice (Oryza sativa L.) is an important cereal crop and staple food of Kashmir valley that represents the only temperate zone of India. Improvement of rice by selection within traditional cultivars or by selecting progeny from crosses between similar traditional cultivars has generally not been promising in enhancing yields as rice productivity in the valley has reached a plateau in the recent years and chances of further yield enhancement are scanty due to low genetic variability in hill cultivars. Therefore, enhancing productivity of rice through novel genetic approaches like heterosis breeding was felt necessary. For efficient hybrid rice breeding programme, availability of stable CMS lines, maintainers, identification of restorers and evaluation of parental lines and conversion of promising maintainer lines in to CMS lines forms an integral part of hybrid rice technology. However, to exploit maximum heterosis using cytoplasmic male sterile (CMS) system in the hybrid programme, one must know the combining ability of different male sterile and restorer lines. Line x Tester (Kempthorne 1957) analysis is one of the most powerful tool for estimating the general combining ability (GCA) of parents and selection of desirable parents and crosses with high specific combining ability (SCA) for the exploitation of heterosis. Key words: Rice, Combining ability, Heterosis, Restorers, Temperate condition Objectives The present study was undertaken with following objectives:  To estimate the combining ability parameters of different male sterile and tester lines.  To determine the nature and magnitude of heterosis for yield and yield components to explore the best combination. Materials and methods The present investigation was conducted during the years 2010-2011 at Mountain Research Centre for Field Crops, Khudwani (34˚ N latitude and 74˚longitude) of Sher -e-Kashmir University of Agricultural Sciences and Technology of Kashmir. The experimental material used for study comprised of two newly developed and well adapted temperate CMS lines viz. SKAU 7A and SKAU 11A and eighteen testers (SKAU-405, Jhelum, K-08-60-2, SKAU-403, SKAU-407, K-08-59-3, China-1007, SR-1, SKAU- 389, K-08-59-1, SKAU-292, SKAU-391, SKAU-354, SKAU-46, Chenab, SKAU-406, K-08-61-2 and SR- 2) that were selected out of the elite germplasm collection maintained at MRCFC, Khudwani. Combining ability analysis for various traits was carried out in rice through Line x Tester analysis of 36 hybrids developed by crossing 18 lines (Males) with 2 CMS lines (Females) along with parents and two standard checks (SR-1 and Jhelum). The 36 hybrids along with 20 parents and standard checks were grown in randomized block design with three replications and were evaluated for traits viz., pollen fertility (%), spikelet fertility (%), number of spikelets/ panicle, number of filled grains/ panicle, panicle length (cm), number of tillers/ plant, plant height (cm), flag leaf area (cm2), biological yield/ plant (g), grain yield/ plant (g), harvest index (%). Days to maturity and days to 50% flowering were recorded on plot basis. Result and discussion Analysis of variance revealed significant differences among genotypes, crosses, lines, testers and line x tester interactions for all the traits. Preponderance of non additive gene effects was realized by higher values of ratio of variances of specific combining ability to variances of general combining ability and average degree of dominance. These results coincide with the findings of Tiwari et al. (2011). None of the parents/crosses were found to be good general/specific combiners for all the traits studied. However, the estimates of GCA effects indicated male parent K-08-61-2 was good general combiner for grain yield plant/plant and other maximum yield contributing traits. Cross combinations SKAU 7A x K-08-61-2, SKAU 7A x SR-2, SKAU 11A x K-08-60-2, SKAU 11A x K-08-59-3 and SKAU 11A x SKAU-389 were found to be good specific combinations for grain yield plant/plant. The cross combinations SKAU 11A x K-08-61-2, SKAU 11A x K-08-60-2 and SKAU 11A x SR-2 were the desirable cross combinations for pollen and spikelet fertility. Saidaiah et al. (2010); Tiwari et al. (2011) also found good general combiners and specific cross combinations for yield and its contributing traits in rice. Assessment of standard heterosis based on standard checks (SR-1 and Jhelum) of effectively restored cross combinations showed that there was significant heterosis for all the traits except number of filled grains/ panicle and the degree of heterosis varied from trait to trait. The entire cross combinations that