EFFECT OF NPK FERTILIZER ON GROWTH AND YIELD OF SWEET POTATO (Ipomea batatas (L) Lam) IN UNWANA SOUTH-EASTERN NIGERIA

Abstract

Sweet potato (Ipomoea batatas (L) Lam) is a vegetable crop often grown without fertilizer by peasant farmers in Nigeria. With the increased pressure on land resources for other competing uses, farmers adopted the use of fertilizer to boost crop production. The experiment was conducted for the purpose of evaluating the influence of NPK fertilizer on the growth and yield attributes of sweet potato. The experiment was carried out under open field condition in 2021 cropping season at the Teaching and Research farm, Department of Horticulture and Landscape Technology, Akanu Ibiam Federal Polytechnic, Unwana, Ebonyi State. The farm is located on latitude 0605’N and longitude 0803’E about 300m above sea level. NPK 20:10:10 compound fertilizer was applied using band method at the rates of (0, 100, 200, 300 and 400kg/ha). The experiment was a randomized complete block design and replicated six times. Each plot size was 4m x 4m and a total of 30 sub plots, while the plants were spaced 90cm x 90cm. data were taken on growth and yield parameters such as; vine length, number of leaves and vines, leaf area, plant girth, number of tubers, fresh weight of tubers, average root length and tuber yield. The results of the experiment show that vegetative parameters significantly (P<0.05) increased from control plots to 400kgNPK/ha except at plant girth where they are statistically the same. Number of tubers significantly (P<0.05) increased from 18 tubers in control to 74 tubers at fertilizer rates between 100 to 300kgNPK/ha. Weight of tubers also increased from 4kg to 19kg between control and 300kgNPK/ha. Total tuber yield recorded at 300kgNPK/ha (47t/ha) differed significantly from other tuber yield recorded. Therefore, 300kg/ha of NPK fertilizer is recommended to farmers in the study area due to an increase in fertilizer above that level will lead to decrease in yield attributes.