A wheat growth model that includes the direct responses of canopy photosynthesis and transpiration to elevated CO2 and the response of crop growth to water stress has been developed and tested. Sensitivity analyses show that different cultivars have quite different responses to changes in ambient air temperature, ambient CO2 concentration and rainfall. Because crops reach maturity earlier under higher temperature, an increase of 3 degrees C may not impose further water stress to growth of a wheat crop in Victoria, Australia. However shorter maturation time may lead to a net decrease in crop biomass accumulation and potential grain yield in some early maturing cultivars. It is suggested that selection of suitable cultivars is one of the key strategies for coping with climate change.