Genetic parameters, correlation and path analysis for 12 yield and quality traits were studied during rabi, 2009-10 in 21 genotypes of rice. High estimates of GCV were recorded for plant height, number of filled grains/panicle and grain yield/plant. Heritability in broad sense was high for all the characters except spikelet fertility. High heritability coupled with high genetic advance as per cent mean were recorded for number of productive tillers/plant, panicle density, number of filled grains/panicle, 1000-grain weight, grain yield/plant and kernel length. Grain yield/plant exhibited highly significant and positive correlation with days to 50 % flowering, plant height, productive tillers/plant, panicle length, panicle density and filled grains/panicle. Path coefficient studies indicated maximum direct positive effect of plant height, productive tillers, filled grains/panicle and kernel length and kernel breadth on grain yield/plant.

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The study was carried out to estimate the combining ability and heterosis for grain yield and its components in rice hybrids. Crosses were effected in line x tester design by using four CMS lines and five restorers as testers and produced twenty hybrids. Analysis of variance for combining ability revealed that variances of SCA were higher than the GCA variances for the traits studied except for 1000 grain weight and spikelet fertility (%) which indicated the predominance of non-additive gene action in the inheritance of traits. The line IR-68897A and the testers IR-79597-56-1-2-1 and WGL-347 were found to be promising general combiners for grain yield per plant and some of its attributes. Estimation of specific combining ability effects revealed that the crosses APMS-6A x IR-79597-56-1-2-1 and IR-79156A x IR-71218-93-1-4-3 had favourable genes for grain yield per plant. The cross IR-68897A x WGL-347 exhibited superior heterosis for number of productive tillers per plant, panicle length, number of filled grains per panicle, spikelet fertility and grain yield per plant over standard check. The cross combinations such as IR-79156A x IR-71218-93-1-4-3, IR-79156A x WGL-347, IR-68897A x IR-79597-56-1-2-1 and APMS-6A x IR-79597-56-1-2-1 showed positive significant heterosis for grain yield. Based on sca effect and standard heterosis the crosses IR-79156A x IR-71218-93-1-4-3 and APMS-6A x IR-79597-56-1-2-1 were found to be promising for grain yield and its components. Hence these cross combinations could be utilized for exploitation of heterosis in rice.

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