GROWTH AND DEVELOPMENT OF SWEET POTATO AS INFLUENCED BY NPK FERTILIZER RATES INTRA-ROW SPACING AND SEED BED TYPES IN THE NORTHERN GUINEA SAVANNA

Farm of Institute for Agricultural Research, Ahmadu Bello University, Samaru (11011’ N070 38Eand 686m above sea level) in the northern Guinea savanna agro-ecological zone of Nigeria to determine the growth and development of sweet potato as influenced by NPK fertilizer rates, intra-row spacings and seed bed types in the northern Guinea savanna. The treatment consisted of three NPK fertilizer rates (0,200 and 400 NPK kg/ha), three intra-row spacings (20, 30 and 40cm) and three seed bed types (ridge, mound and flat). The treatments were laid out in split plot design with NPK fertilizer rates and seed bed types assigned in the main plot and intra-row spacing in the sub-plot, and replicated three times. Result indicated that application of NPK fertilizer significantly enhanced most of the growth components of the crop in both years namely: Vine length, number of branches per plant, cop growth rate, relative growth rate, leaf area index and tuber yield (t/ha). Varying intra-row spacing from 20 to 40cm significantly increased most of the growth components of the crop in both year. Planting sweet potato on the mound performed better than planting on the ridges or the flat which were statistically similar in both years. Based on the results obtained in this study it could be concluded that application of NPK fertilizer at 200 kg/ha, planting sweet potato on 30cm intra-row spacing and using mounds could support good growth and development of sweet potato in both 2011 and 2012 years, respectively.