Increases in atmospheric CO₂ had impacts on plant evolution throughout geological times and enabled mass selection of productive crop ancestors. Recent studies suggest that the ongoing CO₂ fertilisation justifies the establishment of breeding programs to develop crops whose yield will profit from the greater availability of carbon without compromising seed quality. It has been shown that old cultivars may respond more strongly to CO₂ enrichment than their modern counterparts. In order to address this issue, old and modern cereal cultivars (wheat, spelt, barley and rye) and ancestors of wheat (Aegilops, einkorn, emmer) were grown at ambient (380 ppm) and expected future (550 ppm) concentrations of CO₂ in growth chambers simulating a seasonal climate typical for south-west Germany. Phenology, senescence, growth, yield formation and seed quality (ash and nitrogen (N) concentrations) were assessed and the CO₂ response ratio (RR, i.e. performance under elevated v. ambient CO₂) of the parameters was evaluated with respect to the year of cultivar release. Across the 32 accessions tested, seed mass increased by 34% under elevated CO₂, whereas seed ash and N concentrations decreased by 8 and 10%, respectively, with large inter- and intra-specific variation. Yields of modern wheat and barley cultivars proved higher than of old cultivars, but only in barley was RR higher in the older cultivars. Some accessions showed deviations from the negative relationship between seed mass and N concentration, rendering them suitable candidates for developing cultivars adapted to high CO₂.