Growth, Yield and Storability Responses of Sweet Potato (Ipomoea batatas L.) to Nitrogen Source and Application Rate

Abstract

Field and storage experiments were conducted from July, 2022 to January, 2023 in Ibadan, Nigeria, using a split-plot randomized complete block design with three replications to evaluate the effects of different nitrogen rates from organic (poultry manure) and inorganic (NPK 15:15:15) sources on sweet potato growth, yield, and storability. Nitrogen was applied at four levels (0, 45, 90, and 135 kg ha^-1 N). Growth parameters measured included vine length, number of leaves plant^-1, and number of vines plant^-1, while yield parameters included total tuber yield, marketable tuber yield, and non-marketable tuber yield. After harvest, tubers were stored for 10 weeks using two storage methods: elevated platform and bare floor storage systems. Results showed that nitrogen source did not significantly affect the number of leaves or vines, although poultry manure enhanced vegetative growth. Vine length increased significantly at 135 kg ha^-1 N, and poultry manure produced the highest marketable yields. Total yield was highest at 90 kg ha^-1 N. Weight loss during storage decreased with higher nitrogen rates, with the elevated platform method proving more effective in reducing losses than the bare floor. The study concluded that nitrogen application significantly influenced yield and storability, with poultry manure and 90 kg ha^-1 N giving optimum yield. Storage on elevated platforms reduced physiological weight loss showing that improved nutrient management and storage practices enhance productivity and postharvest quality.