Heritability , variability and genetic advance analysis for yield contributing characters in rice ( Oryza Sativa L . )

Genetic variability studies provide basic information regarding the genetic properties of the population based on which breeding methods are formulated for further improvement of the crop. The estimates of heritability, coefficients of variability and genetic advance computed for 12 yield contributing traits. Genetic parameters for yield and its correspondent characters in rice were estimated from a trial with four CMS lines, fifteen testers, three checks and sixty crosses evaluated for twelve characters related to yield. In general, the magnitude of phenotypic coefficient of variation (PCV) was higher than the corresponding genotypic coefficient of variation (GCV) for all the traits, indicating that the apparent variation is not only due to genotypes but, also due to the influence of environment. Therefore, caution has to be exercised in making selection for these characters on the basis of phenotype alone as environmental variation is unpredictable in nature. High estimates of heritability and genetic advance in broad sense and narrow sense were recorded for all characters. High heritability coupled with high genetic advance in percent of mean was observed for all the traits, indicating predominance of additive gene action for these characters. Hence, simple selection based on phenotypic performance of these characters would be more effective. The estimates of additive variance ( 2 A σ ) was found higher than the dominance variance ( 2 D σ ) for all characters. The degree of dominance was greater than the unity for the characters spikelets per panicle, spikelet fertility, 1000-grain weight, biological yield per plant, L/B ratio and grain yield per plant, indicating the presence of over dominance gene action.