EFFECTS OF ORGANIC AND INORGANIC FERTILIZER APPLICATION ON THE PERFORMANCE AND NUTRITIONAL QUALITY OF SWEETPOTATO (Ipomoea batatas L.) IN AKURE SOUTHWESTERN NIGERIA.

Abstract

Sweetpotato (Ipomoea batatas L (Lam), is a dicotyledonous plant, which belongs to the family Convolvulaceae. It originated in Central America, and in the North-western part of South America (Onwueme and Sinha, 1991). It was introduced to Europe in the sixteenth century and it probably came to Africa during the voyages of discovery. It has been grown in the subsistence agricultural system of Nigeria since the 17th century (Leon, 1977). It is perennial, but it is cultivated as an annual with a growing period of three to six months, depending on growth conditions and cultivars (Macdonald, 1963). Cultivars differ from one another in the colour of the root, skin (white, cream, brown, yellow, red or purple), or flesh (white, cream, yellow, orange or reddish purple) in the size and shape of the roots and leaves, in the depth of rooting, the time to maturity, the resistance to diseases and in the texture of the cooked roots (Jennifer, 1992). Sweetpotato is among the worlds most important, versatile, and under exploited food crops (Woolfe, 1992). With more than 133 million tonnes in annual production, sweetpotato currently ranks as the fifth most important food crop on a fresh weight basis in developing countries after rice, wheat, maize, and cassava (ISTRC, 2007). Only in the last decade has the crop been the focus of an intense, coordinated, global effort to realize its full potential as a source of food, feed, processed products, and income for millions of small scale farmers and low-income consumers in Africa, Asia, and Latin America. Three facts have generated growing interest in sweetpotato. First, sweetpotato is typically a small scale farmer crop and often grown on marginal soils with limited outputs. Furthermore, although the crop is grown widely in Asia (31 countries), Africa (39), and Latin America (31), production tends to be concentrated in those countries with lower per capita incomes. Hence, increasing sweetpotato production and utilization is often considered as a means to improve incomes and food security among the