Thesis Abstract

<p> Yam popularly called “<em>Ji” </em>in Igbo Language is a tropical crop belonging to the Family Dioscoreaceae in the genus <em>Dioscorea</em>. It has as many as 600 species out of which six are economically important staple species. These are <em>Dioscorea rotundata</em>&nbsp;(white guinea yam),<em>Dioscorea alata</em>&nbsp;(water yam), <em>Dioscorea bulbifera</em>&nbsp;(aerial yam), <em>Dioscorea esculant</em>&nbsp;(Chinese yam) and <em>Dioscorea dumetorum</em>&nbsp;(trifoliate yam). Out of these, <em>Dioscorea rotundata</em>&nbsp;(white yam) and<em>Dioscorea alata</em>&nbsp;(water yam) are the most common species in Nigeria (Izekor and Olumese, 2010). Yams are grown in the coastal region in rain forests, wood savanna and southern savanna habitats. Yams are perennial herbaceous vines cultivated for the consumption of their starchy tuber in Asia, Africa, Central and South America, and Oceania. Nigeria is by far the world’s largest producer of yams, accounting for over 70–76 percent of the world production. According to the Food and Agricultural Organization report, in 1985, Nigeria produced 18.3 million tones of yam from 1.5 million hectares, representing 73.8 percent of total yam production in Africa. The tubers themselves are also called “yams”. There are many different cultivars of yams example <em>Dioscorea rotundata, Dioscorea bulbifera, Dioscorea esculenta </em>etc. <br></p>

Thesis Overview