Effects of Cultivar and Bulb Size on Growth and Bulb Yield of Onion (Allium cepa L.) in the Northern Region of Ghana

Aims: To determine the effects of cultivar and bulb size at planting on growth and yield of onion production in Ghana.
Study Design: The experiment was laid out as a randomized complete block design and each treatment combination was replicated four times.
Place and Duration of Study: The study was conducted at the experimental fields of the University for Development Studies, Nyankpala in the Northern Region of Ghana from July to October in the year 2012 and repeated during the same period in year 2013.
Methodology: The three onion cultivars used for the study were ‘Bawku red’, ‘White onion’ and ‘Nigel brown’. The bulb sizes used were large (45-60 mm in diameter), medium (30-45 mm in diameter) and small (15-30 mm in diameter) bulbs. Bulbs from these treatment combinations were planted in the field, and growth and yield parameters were measured.
Results: Bulb size at planting influenced vegetative growth and yield parameters of onion. The big bulb gave the best performance in terms of growth and yield whilst the small bulb gave the least of these parameters. No significant cultivar difference was observed in terms of growth, but ‘Bawku red’ and ‘White onion’ had higher bulb fresh mass than the other cultivar.
Conclusion: Results indicated that the highest yield in the northern region of Ghana was obtained with the large (45-60 mm in diameter) bulbs of ‘Bawku red’ or ‘White onion’.