Management of sorghum (Sorghum bicolor) genetic resources among Duupa farmers (northern Cameroon)

The seed system has a direct impact on the genetic Structure of populations of domesticated plants and on its evolution. This system can be characterized by his actors, but also by the nature, the origin and the intensity of exchanges. We characterize the selection practices and the seed exchange for sorghum in the Duupa society in northern Cameroon in order to understand the dynamics of genetic diversity. Farmers maintain about forty landraces sown as a mixture. Each year, farmers select panicles for use in sowing their next crop but they may also introduce seeds which have not been selected. The local seed system leads to frequent seed flow among farmers: 56% of farmer use seeds from harvests of their family or their neighbours. Farmers can give or receive panicles, mainly at threshing times. In addition to this "normal" procedure for the acquisition of seeds, farmers also use seeds exchanged as food on the occasion of visits and ceremonies for sowing. The social relationships among the Duupa directly influence the seed system and are central to the dynamics of genetic diversity.