Genetic variability, heritability and genetic advance in onion (Allium cepa L.)

An experiment was conducted to evaluate 49 diverge genotypes of onion during Rabi season for genetic variability, heritability and genetic advance. Analysis of variance revealed that mean squares due to genotypes were highly significant for 11 characters out of 13 characters. Maximum coefficient range of variation was observed for bolting (%), fresh weight of leaves, neck thickness of bulb, weight of bulb, double onion bulb per plot (%) and bulb yield per plot. Plant height, number of leaves per plant, equatorial diameter of bulb and polar diameter of bulb expressed a moderate coefficient range of variation. The values of GCV were slightly higher than that of PCV for all the traits studied. The high values of GCV and PCV were recorded for bolting (%), fresh weight of leaves, dry weight of leaves, neck thickness of bulb and bulb yield per plot. This indicated the presence of wide genetic variation for these characters. High heritability (broad sense) value were found for bulb yield per plot, weight of bulb, number of leaves per plant, neck thickness of bulb, double onion bulb per plot and TSS of bulb. Moderate values of heritability were observed for plant height, equatorial diameter of bulb and polar diameter of bulb. Genetic advance expressed as per cent of mean was high for bulb yield per plot, weight of bulb, bolting (%), fresh weight of leaves, dry weight of leaves, neck thickness of bulb, double onion bulb per plot (%) and TSS of bulb. The values with moderate magnitude were observed for number of leaves per plant and days to maturity, which may be attributed to the preponderance of additive gene action and passes high selective value and thus, selection pressure could profitably be applied on these characters for their rationale improvement.