Wheat grain represents an important source of carbohydrates, proteins, lipids and minerals. Durum wheat is used mainly for the preparation of pasta, and in some Mediterranean areas is used for bread making. The atmospheric CO2 concentration influences wheat growth, yield and quality. The present work focuses on kernel quality under conditions of elevated [CO2] and subjected, or not, to water stress. The experiments were conducted with the durum wheat (Triticum durum Desf.) varieties cvv. Blanqueta, which is a historical Spanish landrace, and cvv. Sula, which is a modern variety. Sula demonstrated greater kernel weight (KW), insoluble protein (IP) content and amylose content, and also featured better potential test weight (TW) under projected future elevated [CO2] and drought conditions. Blanqueta exposed to drought conditions showed the highest 13C isotopic composition (δ13C) values indicating that, as a consequence of their higher biomass, they were subjected to a more severe stress. Under control conditions of ambient [CO2], the protein concentrations of both varieties were similar. This work provides data about the genetic diversity between a currently cultivated wheat cultivar derived from traditional breeding and another cultivated some decades ago.