Early or late? The role of genotype phenology in determining wheat response to drought under future high atmospheric CO2 levels

The combination of a future rise in atmospheric carbon dioxide concentration ([CO2]) and drought will significantly impact wheat production and quality. Genotype phenology is likely to play an essential role in such an effect. Yet, its response to elevated [CO2] and drought has not been studied before. Here we conducted a temperature‐controlled glasshouse [CO2] enrichment experiment in which two wheat cultivars with differing maturity timings and life cycle lengths were grown under ambient (aCO2 approximately 400 μmol mol–1) and elevated (eCO2 approximately 550 μmol mol–1) [CO2]. The two cultivars, bred under dry and warm Mediterranean conditions, were well‐watered or exposed to drought at 40% pot holding capacity. We aimed to explore water × [CO2] × genotype interaction in terms of phenology, physiology, and agronomic trait response. Our results show that eCO2 had a significant effect on plants grown under drought. eCO2 boosted the booting stage of the late‐maturing genotype (cv. Ruta), thereby prolonging its booting‐to‐anthesis period by approximately 3 days (p