Effect of vine harvesting regimes on root proximate composition of three sweetpotato varieties
A common practice among sweetpotato farmers is the pruning of vines for sale in a field cultivated for root production. While the effects of such practice on root and shoot yields have been extensively investigated, little or no information is available on the effect of the practice on nutritional (proximate) composition of the fresh roots produced. To generate such important information to adequately advise the many farmers that engage in such practice, an experiment was conducted using three popular sweetpotato varieties and four cutting regimes (0, 6, 8 and 10 weeks after planting (WAP). All the normal agronomic practices were observed to ensure adequate plant growth. The three varieties, four pruning regimes and their interactions showed significant (p<0.05) differences for each proximate composition. While pruning led to reduction in root dry matter and carbohydrate contents in Ex-Igbariam and King J varieties, both nutritional components were enhanced by pruning in the Mother’s Delight variety. However, among the pruning regimes, clear trend of increasing root dry matter and carbohydrate contents were observed in King J as the weeks after planting increased. Root carbohydrate of Mother’s Delight reduced as pruning was delayed. Early or no pruning favoured root crude protein accumulation in Ex-Igbariam. In King J and Mother’s Delight, late vine pruning was better for crude protein. The results for ash, crude fibre and fat contents, the relationships among the root proximate content, and the best time to prune each popular variety to achieve higher content of each proximate composition are discussed in the paper.
Keywords: Sweetpotato, vine pruning regime, proximate composition, and correlation