Culture amelioration is one of the major worry of the research to combat millennium challenge (climate change, food security, growth population and other damages). In this context, creation and selection new varieties with a lot of characteristics such as: good productivity, disease resistant, high nutrition values, large adaptabilities capacities, are very important (Lebot, 2013). Sweet potato as some others root and tubers plant are multiplied vegetatively. The sexual reproduction with allele recombination is absent. The capacity of adaptation is week compare to sexual reproduction plant with genes recombination. Germplasms conservation appears important for further action towards improving the culture (Lebot, 2007). Collection, characterization and conservation will be the first action to be done before any others activities leading to the plant improvement.

In Africa, particular in West Africa, sweet potato gain popularities and its richness in vitamin A made it attractive (Bowell-Benjamin, 2007). Despite all these attributes, the culture of sweet potato has biotic and abiotic constraint witch limit it expansion. These constraints lead often on genetic erosion. For root and tubers as sweet potato with vegetative propagation, genetic erosion appears quickly. It is also known that the lost of the genetic diversity is lost of adaptatif potential. Face on this situation it appear urgent to give answer to three important questions such as: what is the degree of genetic diversity of the plant on the area? how farmers manage this diversity? What is the climate influence the genetic structuration of the diversity?