Influence of Bulb Weight at Planting and Drought Stress on Growth and Development of onion (Allium cepa L.) in the Northern Region of Ghana

Aims: To determine the effects of drought and bulb weight at planting on growth and development of onion in the Northern Region of Ghana.
Study Design: Levels of bulb weights at planting and watering regimes were factorially combined and replicated three times in randomised complete block design.
Place and Duration of Study: The study was conducted at the plant house of the University for Development Studies, Nyankpala in the Northern Region of Ghana from the 15th of July to 30th October, 2012 and repeated during the same period and in the same manner in year 2013.
Methodology: Three onion bulb weights namely large bulb (44.3g), medium bulb (26.1g) and small bulb (16.7g) were planted in pots, each of capacity 0.01m3, and subjected to three levels of watering regimes: watering weekly throughout the experimental period, from the time of planting up to three weeks after planting, and from the time of planting up to five weeks after planting. The study was conducted using randomised complete block design with three replications. Growth parameters, plant vigour and bulb yield at harvest were collected for statistical analysis.
Results: Drought stress did not significantly affect vegetative growth and bulb yield of onion but it played a crucial role in influencing plant vigour. Bulb weight at planting, however, influenced plant vigour, vegetative growth and bulb yield at harvest. In general, as the weight of the planted bulb increased, growth and yield parameters also increased in proportion to the weight of the planted bulb.
Conclusion: Onion growers in the Northern Region of Ghana should use large bulb weight (44.3g) at the time of planting in order to get optimum growth and bulb yield at harvest. Growers should also have access to irrigation facilities to supply water on their farms during the time of drought to maintain the vigour of plants especially when the crop is produced by planting small or medium bulbs.