ABSTRACT

Tropical root crops play a key role in the world's food supply. These crops are consumed by a third of the World's population (Chendra, 1991). Cassava, yam and plantain are widely grown by small-scale farmers, and are staple food for millions of people in the humid and sub-huniid regions of tropical A 11ica (I l'l'A Annual report, 1989/90). Of the three crops, cassava, a tiiberous root is by fitr (lie most important, providing more than half (lie food energy consumed by more than 200 million people (ll'l'A Annual Report, 1989/90). Cassava is a major staple food in Nigeria l)1'oVi(1111g about 70% 01 the daily energy intake of over 50% of the Nigeria population. Cereal crops on the other hand, have high caloric energy. Maize has a very h igli yie kl of food energy more (haii wheat and rice, wli icli is 5.4 miii II ion calories per hectare, wheat 3.2 mill ion ca tories and rice 4.3 mill ion per hectare respectively; (FAO, I 968). Maize provide world wide over 40 million tonnes of proteins to humans annually (Obi, 1991). It is one of the World's three most important cereal crops (the others are rice and wheat). maize constitute 64% ol the total daily calorie intake in Nigeria, (Obi,1991). (Okogbenin et al, 1999) reported that Nigeria contributes significantly to world production of cassava, and emerged as the largest producer since the beginning of the 1990, with an estimated output of 3 1.4 metric tonnes in 995. Tuber crops such as yam. cocoyam etc. also play a significant role in the human diet in thetropics and they are of socio-economic important in the lil of' the growers. Yarn productmti is a major agricultural industry in Nigeria which produces about half of the World's total supply, and it's cultivation is done mainly by pe1st11t fhrmers, (Ohigbesan et 1979; and Eze, 1991).