ABSTRACT
Cassava (Manihot esculenta subsp. esculenta) (Allem, 1994; Olsen and Schaal, 1999) is a major source of calories in many countries in the tropics (Nweke et al., 2002). It is estimated that half a billion people in the tropical regions of Africa, Latin America and Asia depend on cassava roots for their supply of energy (Cock, 1985; FAO/IFAD, 2000). Cassava is valued in farming systems in the tropics because the times of planting and harvesting are flexible (Cock, 1982; Coursey, 1973; Coursey and Haynes, 1970). Cassava grows in relatively poor soils, and can be inter-cropped with many other crops (Cock, 1982, 1985). Its production of calories per unit of land, and per unit of labour time, is higher than maize, rice, wheat, and potatoes (Cock, 1982, 1985).
