Sweet Potato

Ipomoea batatas

1. Identification and origin

The sweet potato [Ipomoea batatas (L.) Lam.] is a species of the Convolvulaceae family, native to Central America and northern South America. Domestication occurred more than 5,000 years ago, with subsequent dispersal to the Caribbean, Polynesia and tropical Asia. It is currently grown in tropical, subtropical and warm temperate regions, being one of the most important root crops worldwide.

2. Economic importance

The sweet potato is used for human consumption (fresh, flour, processed products), animal feed and industry (starch, ethanol). It is valued for its high content of carbohydrates, vitamins (particularly vitamin A in orange-fleshed varieties) and antioxidants. In Portugal, it is grown mainly in the Algarve, the Oeste and Madeira, notably the regional “Lira” variety (Aljezur), with Protected Geographical Indication (PGI).

3. Botanical characterization

A perennial herbaceous plant, grown as an annual, with a trailing habit and long, flexible stems. The leaves are simple, alternate, with great morphological variability (lobed or entire). The tuberous roots constitute the storage organ and commercial part of the plant, showing diversity in shape, skin colour and flesh colour (white, yellow, orange, purple). The flowers, when present, are funnel-shaped, similar to those of the genus Ipomoea. Commercial reproduction is carried out by vegetative cuttings.

4. Soil and climate requirements

The sweet potato prefers warm climates, with optimum temperatures between 24–30 °C. It tolerates short periods of drought but is sensitive to frost. It develops best in light, well-drained soils, with a pH between 5.5 and 6.5. Compacted or waterlogged soils favour root rots and reduce the formation of tuberous roots. The crop requires good light and cycles of 90–150 days, depending on the cultivar.

5. Main pests

• Sweet potato weevils (Cylas spp.): boring of the roots and galleries, causing severe losses.
• Whitefly (Bemisia tabaci): sap-sucking and transmission of viruses.
• Aphids (Aphididae): virus vectors and reduced vigour.
• Nematodes (Meloidogyne spp.): root galls and deformation of the roots.
• Noctuids (caterpillars): defoliation and reduction of the photosynthetic area.

6. Main diseases

• Black rot (Ceratocystis fimbriata): dark lesions on the roots and loss of quality.
• Rots caused by Fusarium spp.: vascular necrosis and post-harvest deterioration.
• Feathery mottle virus (SPFMV) and chlorotic stunt virus (SPCSV): responsible for the “sweet potato virus disease” (SPVD), highly destructive.
• Powdery mildew (Erysiphe spp.): white mycelium on the leaves under moderate humidity conditions.
• Brown spot (Alternaria spp.): leaf necrosis.

7. General crop management

Management includes the use of certified, virus-free vegetative material, crop rotation to reduce soil pest pressure, balanced fertilization and regular irrigation. Weeding and weed control are important in the early stages. Harvesting should be carried out carefully to avoid mechanical damage, which favours rots. Storage requires curing conditions (controlled temperature and humidity) for wound healing and prolonged preservation.

Bibliographic references

• EPPO Global Database – Ipomoea batatas.
• CABI – Crop Compendium – Ipomoea batatas.
• FAO (2021). Sweet Potato Production Statistics. FAOSTAT.
• Woolfe, J. A. (1992). Sweet Potato: An Untapped Food Resource. Cambridge University Press.
• Loebenstein, G., & Thottappilly, G. (Eds.) (2009). The Sweetpotato. Springer.