Sweet Potato Plant Information and Variety Selection

Sweet Potato plant physiology and environmental needs

Sweet potato (Ipomoea batatas L) is a dicotyledonous tropical plant of the Convolvulaceae family. It is a perennial plant (only in plant hardiness zones 10-11), although it is mainly grown as an annual crop (in zones 5-9). The plants can grow at 40°N to 32°S latitudes and from the sea level to up to 3,000 m (or 9842.52 feet) altitude. Sweet potatoes are categorized in the same family as the morning glory. Despite their resemblance with the common potatoes, they are two distinct species that are not related (they even belong to different families). However, both belong to the same taxonomic order (Solanales). The edible part of the plant, sweet potatoes, are, in fact, the plant’s storage roots, but leaves and stems are also edible (contrary to those of common potatoes).

The plant has green (sometimes yellowish or purplish) ovate to heart-shaped alternate leaves. The stems are thin and up to 4 meters long, with many lateral stems coming from the main stems. The plants can become 6-10 feet (1.8-3 m) tall and expand in an area up to 8-10 feet (2.5-3 m). The flowers are single, sympetalous, funnel-shaped, white-purple-blue or white-pink, resembling morning glory flowers. The fruits are small smooth capsules (5-8 mm) and contain 1-4 black seeds. The roots of Ipomoea batatas develop storage formations (the commercial sweet potatoes) that vary in shape, and depending on the cultivar; they may be from round to slender and long with a pointing end. The color of the tuberous roots also varies, according to the variety, and can be white, yellow, orange, red, or purple. Sweet potatoes contain mainly amyl, and other substances and are naturally used as a nutrient source for the plant during stressful periods.

The plant originates from Central America and mainly thrives in tropical, subtropical, or monsoonal and temperate climates. Sunny locations (at least 6 hours of direct sunlight) are preferred for the cultivation of these plants. While sweet potato plants are relatively drought tolerant (when the stress lasts for a short period), sufficient water supply positively affects their growth and yield. As a warm-season crop is not very resistant to low temperatures, its planting should occur after the last spring frost, when the soil temperature is above 65 °F (18 °C). Temperatures ranging from 15 °C to 35 °C (57-95 °F) are suitable for the development of plants.

During the Spanish colonial period, sweet potatoes were spread in the Philippines, and since 1604 they were already known in Japan and Europe. In Asia, sweet potatoes are mainly used for the production of alcoholic beverages and animal feed and much less for human consumption. This comes in contrast to the other areas where sweet potato is mainly used for human consumption and secondarily for animal feed. Alcohol is almost never produced by sweet potatoes in these areas.

According to FAOSTAT, the top 5 sweet potato countries are:

China (around 70 million tons)
Nigeria-Malawi
Tanzania
Indonesia
Uganda

Sweet Potato types and varieties

While there is a large genetic variability and hundreds of traditional varieties and landraces are grown globally, only a few are used in larger-scale fields for commercial cultivation. For example, in the USA, the 2 mainly cultivated sweet potato varieties are the ‘Jewel’ and ‘Beauregard.’

All the sweet potato varieties are grouped into 2 main categories based on their flesh texture. Thus, we have:

Moist-fleshed category (e.g., here belongs the Beauregard variety)
Dry-fleshed category (e.g, here belongs to the O’Henry and Hanna variety)

Popular varieties of sweet potatoes

Some well-known varieties of sweet potatoes are:

Beauregard: This variety gives sweet potatoes of light rose skin and orange flesh with medium to very sweet flavors that have good storability. While it is resistant to several important diseases, it is sensitive to root-knot nematodes and bacterial soft rot.
Jewel: It is one of the varieties with the most extended life cycle (up to 135 days) that can give high yields. The sweet potatoes produced have deep orange-brown skin and orange flesh and an extensive storage life. The variety is generally preferred by farmers due to its relatively good resistance to many crop pests and diseases. However, it is susceptible to soil rot.
Evangeline: It has light rose skin and bright orange flesh. The plants are highly resistant to root-knot nematodes but susceptible to sclerotial blight and bacterial root rot. These sweet potatoes store well, but the skin color fades a bit.
Georgia Jet: This variety is cold-resistant, and the plants have a fast-growing rhythm. The sweet potatoes have light rose-purple skin and orange flesh. They are less sweet than the varieties mentioned above but are perfect for baking. Furthermore, the plants give relatively high yields. It is one of the most preferred varieties by amateur farmers.
O’Henry: originates from the Beauregard variety. The sweet potatoes of this variety have white-creamy flesh and skin and a sweet, mild flavor. It was pretty popular in the late 20th century due to its high yields and storability. This type is perfect for baking and frying.

References

Sweet Potato cultivation guide:

Fast Facts about Sweet Potatoes

Sweet Potato Plant Information and Variety Selection

Sweet Potato Nutrition and Health Benefits

How to Grow Sweet Potatoes in Your Backyard

How to Grow Sweet Potatoes for Profit

How to Produce Sweet Potato Slips

Sweet Potato Soil Requirements, Soil Preparation, and Planting

Sweet Potato Water Requirements and Irrigation Systems

Sweet Potato Fertilization Requirements

Sweet Potato Major Pests, Diseases and Weed Control

Sweet Potato Yield, Harvest, Curing, and Storage

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