Résumé
Cultivation of Pearl millet and Sorghum in West africa is still mainly traditional. During the past decades, important human and climatic changes have occured in Sahelian countries. In Niger, the cultivated area and human population have doubled in 25 years. Moreover isohyete 400mm has moved down to the south by 200km in the west and by 100km in the east of the country. The impact of this changes on genetic diversity and adaptation of pearl millet and sorghum landraces is still unknown. In this study, we collected again in 2003 pearl millet and sorghum accessions in the same villages that had been sampled in 1976. Evaluation of morphological adaptation is underway. The analysis of genetic diversity of pearl millet landraces has been performed on more than 500 hundred accessions from 1976 and 2003 collections with 26 microsatellite loci. We will present the first results on the changes in genetic diversity of pearl millet landraces over the past 25 years. (Texte intégral)