Underutilized crops: trends, challenges and opportunities in the 21st century.

Plant biodiversity represents the primary source for food, feed, shelter, medicines and many other products and means that make life on Earth possible and enjoyable (WCMC, 1992; UNEP 1995). The number of plant species used by humans around the world (Table 1) is only one third of the number of species which generations of diverse cultures around the world have drawn upon to develop crops that would meet specific needs. The centres of diversification of most common cultivated species are known today (Zeven and de Wet, 1982), but for many other species of local importance, the knowledge on the distribution of their genetic diversity and use patterns are still largely limited. Increased reliance on major food crops has been accompanied by a shrinking of the food basket which humankind has been relying upon for generations (Prescott-Allen and Prescott-Allen, 1990). This nutritional paradox (Ogle and Grivetti, 1995) has its roots in the agricultural “simplification”, a process that favoured some crops instead of others on the basis of their comparative advantages for growing in a wider range of habitats, their simple cultivation requirements, easier processing and storability, nutritional properties, taste, etc.