T‐FACE studies reveal that increased temperature exerts an effect opposite to that of elevated CO2 on nutrient concentration and bioavailability in rice and wheat grains

Abstract Elevated CO 2 concentration has been reported to decrease grain nutrient concentrations and thus worsen nutritional deficiency and hidden hunger. One nutritional aspect is mineral content, yet mineral bioavailability can be limited by the presence of phytic acid. Given that future climate scenarios predict elevated global temperature driven by elevated atmospheric CO 2 concentrations, we used Temperature by Free‐Air CO 2 Enrichment (T‐FACE) field experiments to investigate whether elevated temperature alters the effects of elevated CO 2 on grain mineral concentrations, grain mineral yields, and their bioavailability in a range of wheat and rice genotypes. We found that the negative effects of elevated CO 2 were compensated for by positive effects of elevated temperature. As a result, the combined elevated CO 2 and elevated temperature increased concentrations of some minerals by up to ~15% in both rice and wheat relative to control conditions. Moreover, the combined elevated CO 2 and elevated temperature did not significantly change total yields of some minerals despite lower grain yields. The combined CO 2 and temperature elevation increased phytic acid concentration in rice by 18.1% but decreased it in wheat by 3.5%. The mineral bioavailability, estimated as the mole ratio of phytic acid to minerals in rice and wheat grains, was limited by the combined CO 2 and temperature elevation in only a few cases. Our results indicate that under future climate conditions of elevated temperature and CO 2 , the nutritional quality of rice and wheat with respect to minerals may remain unchanged.