In plants, antioxidant enzymatic systems play essential roles in modulating dynamic homeostasis of cellular ROS, and thus detoxifying ROS effectively (Liu and Pang, 2010; Zhou et al., 2016b). Here, we investigated several antioxidant enzymatic activities in plants. The activities of antioxidant enzymes tested were no evident difference between the non-inoculated and inoculated plants before saline–alkaline treatment (Figure 5). After 2 and 4 weeks of the stress treatment, the activities of SOD, the first cellular defensive line converting O2•– into H2O2, were significantly increased in the inoculated plants [Figure 5A; F(5,54) = 63.87, P < 0.05]. In contrast to the non-inoculated plants, the activities of CAT converting H2O2 to H2O and O2 were greatly higher in the inoculated plants [Figure 5B; F(5,54) = 48.78, P < 0.05]. The AsA-GSH cycle is an important metabolic pathway that eliminates H2O2 through multiple enzyme catalyzing reactions (Wei L. et al., 2015). The activities of APX [Figure 5C; F(5,54) = 42.93, P < 0.05], DHAR [Figure 5D; F(5,54) = 61.64, P < 0.05], MDHAR [Figure 5E; F(5,54) = 116.41, P < 0.05], and GR [Figure 5F; F(5,54) = 77.76, P < 0.05] were significantly enhanced in the inoculated plants under the stress compared with the non-inoculated plants. Similar results were also observed for the activities of GSH metabolizing enzymes including GPX [Figure 5G; F(5,54) = 79.77, P < 0.05] and GST [Figure 5H; F(5,54) = 26.36, P < 0.05].