 However, concentrations of iron and zinc, which are important for human nutrition, would be lower (Seneweera and Conroy, 1997).Moreover, the protein content of the grain decreases under combined increases of temperature and CO2 (Ziska et al., 1997).Studies using FACE have shown that increases in CO2 lead to decreased concentrations of micronutrients in crop and non-crop plants with negative consequences for human nutrition, including decreased B vitamins in rice.