keywords: Sweet potato, NPK fertilizer, Plant-spacing, plant growth, crop yield
A field experiment was conducted to determine the effect of plant spacing and NPK 15-15-15 fertilizer rates on the growth and yield of sweet potato (Ipomea batatas Lam.) at the Teaching and Research Farm of Federal University of Kashere, Gombe State during the 2019 and 2020 wet seasons. The trial consisted of five plant spacing (30 x 30, 30 x 45, 30 x 60, 30 x 75 and 30 x 90 cm) and five NPK 15-15-15 fertilizer rates (0, 90, 120, 150 and 200 kg ha-1). The treatments were laid out in a randomized complete block design (RCBD), replicated three times. Results from the combined analysis indicated that vine length, number of vines, number of leaves, tuber weight and tuber yield significantly differed due to spacing and NPK 15-15-15 fertilizer rates. However, there was no significant difference (P>0.05) among the treatment means on leaf area plant-1 tuber length and tuber diameter due to plant spacing and NPK 15-15-15 fertilizer rates. There was no significant interaction between spacing and NPK 15-15-15 fertilizer. It can be concluded that spacing 30 × 30 cm was found to produce higher growth attributes over the rest of the treatments, while spacing 30 × 90 produced higher yield attributes over the rest of the treatments. Application of 200 kg ha-1 of NPK 15-15-15 fertilizer was found to produce higher growth yield attributes over the rest of the treatments.