Résumé
Climate change in France, central and southern Europe is expected to provoke more frequent and more intensesummer water deficits, with increased amplitude in temperatures, exposing the same perennial crops to frosts as well as to heat waves and severe droughts. The impacts on sown monospecific grasslands have been assessed using crop models (Durand et al. 2010) but with less accuracy in extreme situations. Since less work has been done on intraspecific genetic variability there is urgent need to investigate both ranges of climate conditions and genetic variability (Poirier et al. 2012). Phenology and plant productivity responses to water, temperature and nitrogen (N) in particular need to be re-assessed over the full range of temperatures projected in the future.