Impacts of climate change on the growth and development of wheat in France What solutions and what actions to develop?

Knowledge acquired over the paste decades on wheat physiology allows for an estimation of the impacts of key climatic factors on wheat physiology, yield components, as well as a quantification of the main climatic risks for the crop. Using historical weather data sets starting in 1955 from a large number of weather stations, we have concluded that a certain number of climatic risks have changed through comparison of two sequences: 1955-1980 and 1981-2005. Despite a significant anticipation of phenological stages, number of grains per m(2) has been significantly affected by an incresase in water stress during stem extension; also, kernel weight is more strongly penalized through the joint effects of increased drought and especially increased heat stress during grain filling. These tendancies vary geographically. Certain regions have been affected early on (mediteranean region), whereas others are almost untouched as yet (western maritime front). Studies using projected future weather data validates this tendancy and allows its extrapolation. We propose adaptation pathways through escape based on varietal earliness and identify new phenological ideotypes and modes of growth better adapted to future risk. As a complement, the interest of selecting for cultivars tolerant to abiotic stresses is put forward, especially cultivars efficient with regards to water use and resistant to high temperatures. For these aspects, simple diagnostic methods and characterization tools are given. Finally, a preliminary analysis of the adaptation of cropping practices (sowing, nitrogen fertilization, lodging control) is initiated.