Ipomoea batatas (L.) Lam. (Convolvulaceae, Dicotyledons) produces storage roots rich in carbohydrates and β-carotene, a precursor of vitamin A, and its leaves are rich in proteins. The roots also contain vitamins C, B complex, and E as well as potassium, calcium, and iron. Purple-fleshed ones contain antioxidants such as anthocyanins. In world crop statistics, the sweet potato is ranked seventh, just after cassava, with an annual production around 9 Mt and a cultivated area of 110 Mha (FAO, 2009). In most developing countries, it is a smallholder crop tolerant of a wide range of edaphic and climatic conditions and grown with limited inputs.