Genetic parameter studies in F4 segregating generation of rice

The present investigation was carried out on F4 families grown from individual F3 plants, selected from a large number of F3 families of rice genotypes. The analysis of variance revealed that mean square due to F4 families were highly significant for all the characters under study indicating considerable genetic variation among the F4 families derived from the crosses. From the values of coefficient of variation (CV), the variability was highest in grain yield panicle-1, followed by number of productive tillers, grain yield, 100 grains weight, number of secondary branches. Flag leaf area, secondary branches panicle-1, grain yield panicle-1 and grain yield plant-1 showed high estimates of GCV and PCV whereas, moderate estimates of GCV and PCV were observed in plant height, primary branches plant-1, number of spikelet, number of filled grains and 100-grain weight. Low estimates of GCV and PCV were found in panicle length and spikelet fertility. The estimates of GCV and PCV values for number panicle plant1, 100-grain weight, primary-branches panicle-1and panicle length showed wide difference which indicated the greater role of environmental factors influencing the expression of these characters. The estimates of heritability was very high for number of spikelet panicle-1, number of filled grains panicle-1, plant height, flag leaf area, secondary branches panicle-1, grain yield plant-1, grain yield panicle- and spikelet fertility. Panicle number, primary branches panicle-1 and 100-grain weight have moderate heritability. High heritability coupled with high genetic advance was observed for flag leaf area, grain yield panicle-1, grain yield plant-1 and secondary branches panicle-1 indicating that the expression of these characters is under the control of predominant additive gene actions and hence selection would be effective.