Figure 4. Effects of Na₂CO₃ on ROS production and antioxidant enzyme activities in Puccinellia tenuiflora roots.

(A) O₂⁻ generation rate (white diamonds) and H₂O₂ content (black diamonds); (B) glycolate oxidase (GO) (white diamonds) and superoxide dismutase (SOD) (black diamonds) activities; (C) peroxidase (POD) (white diamonds) and catalase (CAT) (black diamonds) activities; (D) ascorbate peroxidase (APX) (white diamonds) and dehydroascorbate reductase (DHAR) (black diamonds) activities; (E) monodehydroascorbate reductase (MDHAR) (white diamonds) and glutathione reductase (GR) (black diamonds) activities; and (F) glutathione peroxidase (GPX) (white diamonds) and glutathione S-transferase (GST) (black diamonds) activities. The values were determined under control, 150 mM Na₂CO₃ for 12 h, 200 mM Na₂CO₃ for 12 h, 150 mM Na₂CO₃ for 24 h, and 200 mM Na₂CO₃ for 24 h. The values are presented as means ± standard deviation (n = 3). Different letters indicate significant differences among different treatments (p < 0.05).