Onion is commonly established in the field either by direct sowing, or by transplanting seedlings from seedbed or from sets depending on the growing conditions of the specific region and grower interests. However, the optimum transplanting age in onion growing areas and Ethiopia is not well established. A field experiment was conducted at Alawuha kebele of North Wollo zone to optimize seedling age of onion varieties in 2021/2022 cropping season under irrigation. Adama Red, Bombay Red and Nafis and four seedling ages (30, 40, 50 and 60 days) were laid down in RCBD replicated three times. Phenology, growth and yield parameters were collected using standard procedures and analyzed using SAS software. Results revealed significant (P < 0.05) difference for plant height, leaf length, neck diameter and bulb length; while their interaction was not significant. Nafis gave significantly longer bulb (4.89 cm) than Adama Red (4.70 cm) and Bombay Red (4.45 cm). Nafis derived from 40 days old seedlings produced the highest average bulb weight (100.10 g), marketable (37.68 t ha-1) and total (37.96 t ha-1) bulb yield. The overall result indicated that onion establishment from 40 days old seedling may be good for yield of onion in northeastern Ethiopia.

Keywords: Allium cepa, transplanting age, yield, varieties