Effect of nutrient management and time of vine cutting on orange and white-fleshed sweetpotato varieties in Southern Nigeria

The study was conducted in 2016 and 2017 cropping seasons at the research farm of Akwa Ibom State University, Obio Akpa, Nigeria to examine the effects of nutrient management, vine cutting time and variety on growth, yield and quality of sweetpotato. The experiment was laid out as split-split plot in a randomized complete block design with three replications. Results revealed that a combination of 2.5t/ha poultry manure + 200kg/ha NPK fertilizer or poultry manure alone significantly increased vine length, number of branches/plant, shoot dry matter and fresh shoot biomass compared to application of 400kg/ha inorganic NPK fertilizer alone and the no fertilizer application. The highest storage root yield and carotenoid content were obtained from combined application of 2.5t/ha poultry manure + 200kg/ha NPK fertilizer. A mixture of manure and fertilizer also significantly reduced decay of storage roots. No vine cutting significantly increased fresh shoot biomass but reduced carotenoid content compared to cutting at 16 or 17 WAP, while date of cutting had no effect on storage root yield. Sweetpotato variety white – fleshed TIS 87/0087 had significantly higher fresh shoot biomass and storage root yield than orange – fleshed Umuspo 3 but carotenoid content was higher in the latter than the former.