The contribution of exotic material – rye introgression lines, synthetic and landrace-derivatives – in wheat has been demonstrated a valuable resource under drought, heat and yield potential conditions. Enhanced tolerance of exotic material to abiotic stress has been associated with lower leaf respiration rates, deeper root system, early ground cover, increased water soluble carbohydrates and cooler canopies, among others. In this study, a panel of 150 elite spring wheat genotypes including many landraces, introgression and synthetically derived lines was evaluated over two years under heat stress and favorable conditions. In total, 91% of the lines that beat the best check under heat stress had exotic material in their pedigree (while their representation was only 43% of the total). The best lines presented up to 28% yield increase in comparison with the best check, associated with higher radiation use efficiency (RUE) and cooler canopies. Most of these lines were derived from physiological trait (PT) strategic crosses based on diurnal canopy temperature (CTd) and normalized vegetation index (NDVI). Further studies that included some of these PT lines together with their parents (elite lines, Mexican landraces and synthetic derived lines) showed that, in addition to CTd, there were significant differences in night canopy temperature (CTn) among the five different groups studied (check, elite parent, landrace parent, synthetic derived parent and PT line). CT was measured at different times during the day and night and results showed that PT lines presented lower CTn in comparison with elite checks (P<0.05) indicating higher night transpiration rates. The parental lines who presented the lowest CTn were Mexican landraces and synthetic derivatives suggesting opportunities for exploiting night temperature as a heat tolerance associated trait.