Oryza glaberrima

Oryza glaberrima, commonly known as African rice, is one of only two domesticated rice species in the world.

While it is a major crop, it is often overshadowed by the higher-yielding Asian rice, known as Oryza sativa. In West Africa, African rice accounts for approximately 20% of commercially grown rice. This species is highly valued for its resilience and distinct nutty flavor. It remains a vital part of local diets and cultures, even as newer varieties become more common.

The plant possesses unique biological mechanisms that allow it to thrive in difficult environments. It exhibits profuse vegetative growth, which helps the plant smother competing weeds. African rice is notably resistant to several pests and diseases. These include the African rice gall midge, parasitic nematodes, and the rice stripe necrosis virus. It also resists the parasitic plant known as Striga. Furthermore, the plant can survive in soils with iron toxicity or low fertility. It is highly adapted to both drought and deep-water conditions. Some varieties even grow rapidly when submerged to survive short floods.

There are many different types of African rice, often categorized by their physical traits. The plants are generally tall, though some floating varieties can grow even higher. These floating types may branch and grow new roots from higher nodes on the stem. The grains are typically small and pear-shaped with reddish bran. The hulls can range in color from green to black. Some cultivars are named for their specific textures, such as aspera, which means "rough." Others include varieties like rigida, meaning "rigid," or rustica, meaning "coarse."

History shows that humans likely domesticated this species independently of Asian rice. The domestication of Oryza glaberrima occurred about 3,000 years ago. This process began in the inland delta of the Upper Niger River, located in modern-day Mali.

As the Sahara region became drier over time, the wild ancestor, Oryza barthii, retreated. This climate shift likely forced the rice to rely more on human irrigation. From the Niger River, the crop spread throughout West Africa and even reached the Zanzibar Archipelago.

African rice has a significant history involving global movement. During the transatlantic slave trade, the rice was brought to the Americas. It arrived in Brazil around the 1550s and reached the United States by 1784. Enslaved farmers brought both the seeds and the specialized knowledge required to cultivate it. Because African rice tolerates brackish, or salty, water, it was well-suited for coastal deltas. In the United States, the heirloom cultivar Carolina Gold became quite popular. This variety was eventually lost during the American Civil War.

Cultivating African rice presents specific challenges regarding yield and processing. One major issue is shattering, which occurs when grains fall from the plant naturally. On average, about half of the grains in some varieties can be lost this way. However, if farmers bag the rice heads before they are ripe, the yield can match that of Asian rice. The grains are also more brittle than Asian varieties. This means they are more likely to break during industrial polishing. Despite these issues, many farmers prefer it for its nutritional content and taste. In Nigeria, it is specifically used to produce Ofada rice.

Modern science is now attempting to combine the strengths of both rice species. For many years, crossbreeding between African and Asian rice was very difficult. The offspring of these crosses were often rarely fertile. However, scientists developed the NERICA program, which stands for "New Rice for Africa." Using techniques like embryo rescue, researchers created over 3,000 crosses during the 1990s. These NERICA cultivars aim to combine the disease resistance of African rice with the high yields of Asian rice. While results have been mixed, this work connects ancient agricultural traditions with modern genomic science.