Estimates of heritability, genetic advance and correlation between yield and its components in onion (Allium cepa L.)

The rate of selection process depends upon the heritability of the character involved; hence the genetic variability and correlations for quantitative and qualitative characters are of great value in selecting desired genotypes in plant-breeding programme. The knowledge of association of yield components with yield and among themselves will be helpful in the improvement of complex character like yield for which direct selection is not very effective. The aim of the present study was to estimates the magnitude of genotypic and phenotypic variation, heritability, genetic advance and correlation for selecting superior genotypes in relation to yield. The experiment was laid out with 22 onion genotypes at experimental farm of National Research Centre for Onion and Garlic, Rajgurunagar, Pune in a randomized block design with two replications in late Kharif season. The data was taken on quantitative and qualitative attributes along with the yield. The genotypic coefficient of variations was low as compared to the phenotypic variations. The phenotypic coefficient of variations was lowest for the character T.S.S., while highest for the character percentage of bolters. The genotypic coefficient was lowest for the characters dry matter of leaves and percentage of "B" grade bulb, while highest for the character percentage of bolters followed by percentage of doubles. The maximum phenotypic variability was found in the character bulb weight followed by percentage of doubles and marketable yield. The characters, percentage of 'A' and 'B' grade bulbs showed moderate variability. Similar trend was observed in respect of genotypic variability. The estimates of phenotypic variance were higher than the genotypic variances. Heritability percentage was observed that the most of the characters studied had moderate heritability value. Very high estimates of heritability percentage were observed in character polar diameter of bulbs followed by T.S.S. The other character like, total yield neck thickness and percentage of 'A' grade bulbs showed moderate heritability percentage. The highest genetic advance was observed in character bulb weight, it was followed by percentage of 'A' grade bulbs. The character number of leaves and percentage of dry matter of leaves was recorded with lowest genetic advance. The perusal of results indicated that, phenotypic co-efficient of variation was higher than genotypic co-efficient of variation, indicated that all the genotypes tested, phenotypical