Planting Dates and Nutrition Management Regimes Impact Positively on Bulb Size, Quality and Yield of Rain-fed Onion

Abstract

Bulb size, appropriate time of planting and sufficient growth nutrients may determine the quality of seeds and productivity of onion. Studies were conducted during the cropping seasons of year 2015 and 2016 to assess the effects of planting date and nutrients management regimes on bulb size, quality and yield of rain-fed onion using seeds of variety Prema as planting material. Three levels of transplanting dates namely early transplanting (N1)), transplanting of seedlings two weeks after early transplanting (N2), and transplanting of seedlings four weeks after early transplanting (N3) were factorially combined with the following six fertilizer application regimes: F1 (no fertilizer application), F2 (application of 375 kg/ha of NPK 23:10:10), F3 (application of 10 t/ha fertisoil compost), F4 (application of 187.5 kg/ha of NPK 23:10:10 plus 5 t/ha of fertisoil compost), F5 (application of 125 kg/ha of NPK 23:10:10 plus 6.6 t/ha of fertisoil compost) and F6 (application of 250 kg/ha of NPK 23:10:10 plus 3.3 t/ha of fertisoil compost). Seedlings from the above treatment combinations were planted using RCBD in three onion growing communities in the Northern Region of Ghana. At harvest, bulbs were sorted into three groups (large, medium and small bulbs). Results from the studies indicated that in each group of bulb size, N1 x F4 plants produced the highest bulb fresh weight and bulb diameter. Plants from these regimes also produced the highest bulb quality and bulb yield. Farmers should nurse onion seeds early, latest by first week of June in the rainy season, so as to transplant seedlings by first week of July and apply 187.5 kg/ha of 23:10:10 NPK plus 5 t/ha fertisoil compost for improved bulb sizes in the study area.