Effect of Planting Distance and Harvesting Period on the Composition, and Quality Parameters of Orange Fleshed Sweet Potato Varieties (Umuspo-1 and Ex-Onyunga)

Abstract

The aim of this study was to determine the best planting practices for two bio fortified Orange Fleshed Sweet Potatoes (OFSP). The study investigated the effect of spacing (20, 30 and 40 cm) and maturity (12 and 16 weeks) period on the proximate composition, α-amylase, reducing sugar as well as total and soluble carbohydrates of two OFSP varieties (Umuspo1 and Ex-Onyunga). The moisture content of OFSP ranged from 68.30 to 82.67 % at 12 weeks and 63.73 to 74.67 % at 16 weeks, while the ash, fat, fibre, protein and carbohydrate at 12 weeks maturity period were from 0.47 to 1.16, 0.47 to 3.13, 0.41 to 4.41, 1.88 to 2.88 and 10.52 to 25.46 % respectively. On the other hand, ash, fat, fibre, protein and carbohydrate at 16 weeks maturity period ranged from 0.63 to 1.03, 0.47 to 3.13, 0.87 to 3.77, 1.58 to 2.44 and 13.32 to 30.07 % respectively. The results also indicated that Ex-Onyunga variety planted at 40 cm spacing harvested at the period of 12 weeks had the highest protein content (2.88%) which was significantly different (p<0.05) from OFSP harvested at 16 weeks. The α-amylase content at 12 weeks and 16 weeks maturity period ranged from 18.94 to 45.65 μg/g and 19.21 to 43.46 μg/g respectively. The reducing sugar content ranged from 166.32 to 234.21μg/g under various planting spacing conditions at 12 weeks and 164.21 to 208.07μg/g at 16 weeks maturity period. The result of soluble carbohydrate content ranged from 43.57 to 51.19μg/g at 12 and 16 - weeks maturity period. Spacing and maturity period had significant (p<0.05) effects on the proximate composition and other parameters evaluated. This research has established a frame work for Agriculturists on the best planting spacing to be adopted for optimum nutrient yield of the two OFSP varieties.