Effect of Planting Dates and Fertilizer Rates on the Growth and Yield of Sweet Potato (Ipomoea batatas L.) In WUKARI, Taraba State

Abstract

A field experiment was conducted at the teaching and research farm of the Federal University Wukari, Taraba State, Nigeria to determine, evaluate and compare the effect of planting dates and fertilizer rates on growth and yield of sweet potato, using three planting dates: planting date one (July 4), planting date two (July18) and planting date three (August 1) for both 2017 and 2018 cropping seasons, and four fertilizer rates: F0 (0kg/h), F1 (30kg/h), F2 (60kg/h) and F3 (90kg/h). The treatments were arranged in 3 x 4 split plot factorial design combinations replicated three times. Measurements were taken on the growth and tuber yield at harvest such as the length of primary veins, number of secondary veins, number of leaves, number of tubers and tuber weight. Data collected were analyzed using ANOVA and the significant means separated using Duncan multiple differences at 5% probability level. The result of the experiment indicated that both main effects (planting dates and fertilizer rates) had significant influence on all of the traits measured. Similarly, the interactive effect of planting dates and fertilizer rates significantly affected all of the traits measured, except leaf area which is not significantly influenced by the interactive effect of planting dates and fertilizer rates. The significantly highest weight of tuber per plant was obtained from the planting dates at PD1, PD2 and PD3 (1.09, 1.56 and 1.10 respectively in 2017 cropping season and 1.00, 1.51 and 1.03 respectively for 2018 cropping season). Fertilizer rates enhanced growth and yield performance on the planting dates used. Highest yield values were observed in planting date 2 (PD2). Highest value in all the yield characters measured was observed in planting date 2 (PD2) at fertilizer rates of F3 and F2 (90kg/h and 60kg/h respectively). Based on the findings from this research, planting date 2 (PD2) with 60kg/ha (F2) of fertilizer application rate is recommended. Generally, all traits except the leaf area were significantly affected by the interactive effect of planting date and fertilizer rate, indicating that determining fertilizer rate for each planting date by considering their vegetative growth and yield habit is very important in crop production. Further research should be repeated under rainfed conditions at different locations.