Tuber

الوصف

The major edible species of yam of African origin are white Guinea yam (D. rotundata Poir.),yellow Guinea yam (D. cayenensis Lam.),and trifoliate or bitter yam (D. dumetorum Kunth). Edible species from Asia include water or greater yam (D. alata L.), and lesser yam (D.esculenta [Lour.] Burkill). Cush-cush yam (D. trifidaL.)originated from the Americas.White Guinea yam and water yam are the most important in terms of cultivation and use.Yam is grown in about 51 countries in the tropics and subtropics,with yields averaging about 11 metric tonnes/hectare in the major producing countries of West Africa (Nigeria,Cote d'Ivoire,Ghana, and Benin).
"There are different types of yam tubers produced in Nigeria, such as water yam, cocoyam and yellow yam; but the ones needed for exportation are the sweet and pound able ones.
  Specification & Grades: Yam specification varies from one buyer to the other in terms of weight,length and diameter. Generally exportable yam should have the following characteristics.
 
  i.Diameter- 3.5-4.Scm

1. Length- 15-40cm
2. No hair(No fibers)
3. No fingers(branches)
4. Very smooth body with no sand(if at all it should be very minimal)
5. No injury(if at all it should be very minimal)
6. Not too big(enough for a family to eat at once)