Yam (dioscorea spp.) is a multi-species crop that originated principally from Africa and Asia before spreading to other parts of the world (Hahn et al.,1987). It belongs to the family of dioscoreae within the genus dioscorea and serves as a staple crop in west Africa.(Asiedu et al., 1992). There are many cultivars of yam, though only six are important as staple foods in the tropics. the economically important species grown are Dioscorea rotundata(white yam),D.alata (yellow yam),D.bulbifera (aerial yam), D.esculenta (Chinese yam) and D.dumenterum (trifoliate yam). Yam tubers which is the most important part of the plants can be stored longer than other root and tuber crops. This ensures food security even in times of general scarcity. Yam is the third most important tropical root and tuber crop after cassava and sweet potato (fu et al., 2005). West Africa is the leading producer of yam and grows over 90% of the worldwide production (40 tonnes fresh tuber/year) followed by the west Indians where Jamaica is the leading producer (FAOSTAT,2004). Nigeria is the world’s largest producer of yams followed by Ghana, ivorycoast and togo (FAO,2003). Both fresh tubers and yam flour are now exported from Ghana and Nigeria to developed countries such as united kingdom and united states of America. These are mostly patronized by emigrants from growing regions according to the Nigerian export promotion council (NEPC) Nigeria realized N56 billion in 2007. Sustainable production and utilization of yam are important steps in enhancing food security.
