Résumé
Millet is the world's sixth most important cereal in terms of production, but plays a vital role in food security in the arid and semi-arid regions of Africa and India. Drought, the frequency of which is expected to increase with climate change, is the most important factor limiting its production. The plant root system is responsible for acquiring water and mineral elements through soil exploration, which depends on root architecture, and absorption capacity, which depends in part on root anatomy. The selection of root traits favorable to hydromineral nutrition therefore appears to be a potential way of increasing crop performance and resilience.A panel of millet varieties will be phenotyped in the field for their agro-morphological traits, architecture and root anatomy under irrigated and early water stress conditions. The lines of this panel will also be genotyped by sequencing. The aim of the thesis work will be to exploit these data (available at the beginning of the thesis) to 1) identify the regions of the genome controlling root anatomy by association genetics (GWAS), 2) study the correlations between root traits, water nutrition and drought tolerance, and 3) identify and characterize the physiological mechanisms involving root anatomy for drought tolerance.