Morphology and yield potential of sweet potato (Ipomoea batatas L.) as influence by NPK fertilizer rates and vine cutting length in Jos Plateau State, Nigeria

The experiment was carried out in the demonstration farm of Federal College of Forestry Jos during the 2019 farming season to determine the effects of NPK fertilizer rates and vine cutting lengths on the growth and yield of sweet potato. The treatments include, three rates of NPK fertilizer (0, 0.2 and 0.4 kg) allocated to the main plot and two vine cutting lengths of (30 and 40 cm) in the sub plot in 3 x 2 factorial split plot design. The parameters assessed includes; number of branches, length of vine, leaf count, leaf area index and vine girth at 2, 4, 6, 8 and 10 weeks after fertilizer application (WAFA) and tuber count, tuber length, and yield weight at harvest. The parameters were subjected to analysis of variance and the means separated using the LSD (Least significant difference) at (p≤0.05). The results on the number of branches shows significant difference at 2 and 6 (WAFA) and at 4 WAFA for both treatments and positive interaction at 8 WAFA. Vine length showed no statistical difference at 4 WAFA, but significance at 2 and 8 WAFA with positive interaction at same weeks. The results on leaf count showed significance across the weeks with fertilizer rates and at 2 WAFA with vine cuttings with no interactions across the trend. The leaf area index showed no statistical difference with all the treatments as indicated. The vine girth showed significant difference across the weeks with fertilizer rates, and at 10 WAFA with the vine cuttings with no interactions. The yield parameters showed significance and positive interaction across with both treatments on tuber count, tuber weight and tuber length respectively. In conclusion, these results indicated that planting sweet potato in Jos plateau with a fertilizer rates of (0.4 kg/2m2 experimental plot) and 40 cm vine length could impact the growth and yield positively.