Genetic variability and correlation studies in onion (Allium cepa L.) genotypes

Onion (Allium cepa L.) is one of the most valuable vegetable cum spice crop belongs to the family Alliaceae with chromosome number 2n=16. The existing knowledge about onion genetic diversity and resources is limited or one has to review periodically which helps in the efficient management of germplasm and selection of parents for crossing. Hence the present investigation was carried out with 40 onion genotypes for genetic variability which revealed that the environmental influence was very less on expression of these characters as it was evident by narrow gap between genotypic and phenotypic coefficients of variation. Genotypic and phenotypic coefficients of variation were moderate to high, for all the characters studied except for days to first flowering, days to 50 per cent flowering and TSS. Moderate to high heritability was observed for all characters and high genetic advance as per cent mean indicating that simple selection would be sufficient for these traits to bring genetic improvement. Individual bulb weight had positive and highly significant association with plant height, number of leaves, neck thickness and bulb diameter. Strong association of these traits revealed that selection based on these traits would ultimately improve the individual bulb weight per plant and it is also suggested that hybridization of genotypes possessing combination of such characters is most useful for obtaining desirable high yielding segregants.