Preliminary studies on the response of onion (Allium cepa L.) to planting depth and NPK fertilizer application

Abstract

AbstrActStudies were conducted at the department of Agronomy of the University fordevelopmentStudies in Nyankpala,ghana, from July tooctober 2011 and repeated in the same period in2012 to determine the response of onion to depth of planting and fertilizer application.onionbulbs of average fresh weight of 24 g were planted 0, 2, 4 and 6 cm deep from soil surface, andNPK (15:15:15) fertilizer at the rate of 0, 85, 170 and 255 kg ha-1was applied at the time ofplanting and 2 weeks after planting.the treatment combinations were replicated four times inrandomized complete block (rCb) design.the results indicated that planting 4 cm deep, andapplying NPK fertilizer at the rate of 85 kg ha-1produced the highest bulb size and fresh weightat harvest.bulbs planted 2 cm deep, which received no fertilizer application, produced the high-est number of bulbs at harvest, whilst those planted at the depth of 6 cm and fertilized with 170kg ha-1of NPK gave the least number of bulbs. Leaf production was highest when bulbs wereplanted 2 cm deep, and no NPK fertilizer application.tiller production was also highest whenbulbs were planted 4 cm deep and no NPK fertilizer application. In onion production, therefore,whilst NPK fertilizer may not be required for vegetative growth, it is important to apply thefertilizer to enhance bulb production. onion growers in the study area should plant onion bulbson Nyankpala soil series 4 cm deep, and apply NPK fertilizer at the rate of 85 kg ha-1to the soilfor good bulb yield.Original scientific paper. Received 03 Apr 14; revised 16 Sept 14.