Landrace diversity and heritage of the indigenous millet crop fonio (Digitaria exilis): Socio‐cultural and climatic drivers of change in the Fouta Djallon region of Guinea

Societal Impact Statement White fonio ( Digitaria exilis Kippist Stapf) is an understudied millet crop, indigenous to West Africa and cultivated in the region largely through traditional practices. This species is climate‐resilient, fast‐growing, nutritionally rich, and provides livelihoods and food security to rural communities. Through collaboration with smallholder farmers in the Fouta Djallon region, Guinea, this study investigates how the diversity and selection of fonio landraces has changed in living memory. This research provides insight into how climatic and socio‐cultural changes affect the cultivation of fonio varieties and other indigenous crops, and why they should be conserved and further involved in rural development programmes. Summary The millet crop white fonio ( D. exilis ) isa staple crop feeding thousands of people across West Africa. The Fouta Djallon highlands region of Guinea is a hotspot for its cultivation, with known high genetic diversity. Our study utilises data from ethnobotanic interviews and plant specimen and seed collections, working with farmers from 15 communities in this region with the aim to investigate the diversity of landraces and popularity of fonio within the current agricultural systems, in the present, and changes over the past 50 years. A total of 24 named varieties of fonio were recorded and described, along with other commonly cultivated food crops. This includes two lost varieties now no longer cultivated. We also describe the methods for cultivation, grain processing and food preparation. The priority and popularity of cultivated fonio landraces, and other crops, has changed, due to the consequences of social and environmental change in living memory. The diversity of fonio landraces are maintained as an adaptation to historical climatic changes, and there is an increasing preference towards varieties with a longer growing period and more reliable high yield to the detriment of early season varieties.