Superoxide Dismutase Plays an Important Role in Maize Resistance to Soil CO2 Stress

CO₂ capture and storage (CCS) has the risk of CO₂ leakage, and this leakage always increases soil CO₂ concentration, and the long-term CO₂ stress damages crop production in farmland. Using maize, the growth characteristics, such as plant height and yield, and physiological indexes (osmoregulation substances and antioxidant enzymes) were explored under different simulative CO₂ leakage conditions. Further, the relationship between maize physiological indexes and soil CO₂ concentration was analyzed, showing that soil CO₂ stress inhibited maize growth to a certain extent, resulting in shorter plants, thinner stems and lower kernel yield. With an increase in soil CO₂ concentration, the contents of malondialdehyde, soluble sugar and soluble protein in maize leaves increased; with continuing stress, the increase rate of malondialdehyde was greatly augmented, whereas the increase rates of soluble sugar and soluble protein decreased. With extended CO₂ stress, the activity of the enzyme superoxide dismutase (SOD) increased continuously, while the activities of catalase and peroxidase first increased and then decreased. Superoxide dismutase activity was closely correlated with soil CO₂ concentration (r = 0.762), and responded quickly to the change of soil CO₂ concentration (R² = 0.9951). Therefore, SOD plays an important role in maize resistance to soil CO₂ stress. This study will help further understanding of the mechanism of maize tolerance to soil CO₂ stress, providing a theoretical basis for agricultural production in CCS project areas.