Wheat annual production is likely to decline in some regions of the world, associated to rising temperatures (IPCC, 2007). Shorter growing seasons will have a negative impact on processes underlying yield formation and resource capture, while sub-optimally high temperatures are documented to cause irreversible changes in spike fertility. In this paper, we integrate a series of field, glasshouse experiments and simulation outputs to investigate the quantitative response to increasing temperatures of key processes underlying yield in wheat genotypes contrasting for specific traits. Germplasm consisted of closely related lines differing for one or more of the following traits: transpiration efficiency, water soluble carbohydrates accumulation, spike fertility and tillering. In addition, the role of glasshouse experiments to predict trait ranking or performance in the field in warmer environments is discussed.