Minor root and tuber crops in Africa: Cocoyams (Colocasia esculenta and Xanthosoma sagittifolium)

Cocoyams [taro: Colocasia esculentum (L.) Schott and tannia: Xanthosoma sagittifolium (L.) Schott] are staple tuber crops in many countries in Africa, Asia and the Pacific. This review aims to present the value of cocoyam as a minor tuber crop and the extent and challenges of its production in Africa. Cocoyams are primarily grown for their edible corms or cormels, although other parts, such as stalks, leaves and inflorescence, are used for human consumption. Cocoyams are categorized as neglected food crops mainly grown for subsistence use. Taro is more widely grown than tannia globally. Taro is cultivated all over Africa, although West and Central Africa are the main producing regions. Tannia is mainly grown in West Africa where it is still less common than taro. Production of tannia is generally minimal and rarely appears in cocoyam output statistics for the continent. Africa is the main producer of cocoyam, accounting for over 70% of the global output; the bulk of production occurs in the West and Central African region. Despite the high production, food value and economic opportunities, African cocoyam is rarely sold in the international markets. The crop is cultivated to meet food security at small-scale and family farms. It is mostly consumed and marketed locally in fresh state. Cocoyams are commonly produced by resource-limited smallholder farmers who are mostly women. The crop is cultivated on marginal lands where primitive technologies with little inputs are employed. The crop receives little attention from mainstream research organizations in Africa. Other constraints limiting cocoyam production in Africa include a shortage of planting materials, lack of improved high-yielding cultivars, and paucity of information on the proper agronomic practices, and insect pests and diseases, among others. Industrial use and new product developments of cocoyam in Africa should be explored to enhance the crop's economic value, and by extension attract research attention