Genetic Variability, Heritability and Genetic Advance for Yield and Quality Traits in Onion (Allium Cepa L.) Genotypes During the Rabi Season

The present investigation was conducted to assess genetic variability, heritability and genetic advance for morphological and biochemical traits in onion (Allium cepa L.) during the Rabi season of 2024-25 at the University of Horticultural Sciences, Bagalkot, Karnataka. Seventy onion genotypes and six standard checks were evaluated using an augmented block design. The results revealed considerable variability among the genotypes for the evaluated traits. Among morphological characters, G9 recorded the maximum plant height (74.21 cm), G63 the highest number of leaves (16.44), G12 the highest collar girth (22.00 mm), G5 the maximum polar diameter (82.05 mm) and G65 the highest equatorial diameter (89.25 mm) and bulb weight (232.50 g). For biochemical traits, G60 recorded the highest total soluble solids (27.30 °Brix) and FRAP antioxidant activity (1.25 mg AAE/g), G25 the highest dry matter content (39.05%), G58 the highest ascorbic acid content (15.36 mg/100 g fresh weight), G5 the highest total flavonoid content (3.86 mg QE/g fresh weight) and G67 the highest total phenolic content (93.97 mg GAE/g fresh weight). Number of leaves exhibited a GCV of 22.98%, heritability of 83.78% and GAM of 43.89%. Among biochemical traits, FRAP antioxidant activity recorded the highest GCV (60.87%) and GAM (115.29%), followed by dry matter content (55.99%), total phenolic content (53.55%) and total flavonoid content (46.34%). These findings indicate substantial genetic variability and promising selection potential for improving bulb characteristics, quality and antioxidant properties. The identified genotypes may serve as valuable material for further evaluation and onion breeding programmes.