Effects of exogenous Spd on antioxidant enzyme activities and MDA content and ROS in leaves of tomato seedlings grown in nutrient solution or in 75 mM saline-alkaline solution (nutrient solution with 75 mM saline-alkaline solution; NaCl:Na
= 1:9:9:1) with or without 0.25 mM Spd. (A) delegated SOD activity; (B) delegated POD activity; (C) delegated CAT activity; (D) delegated MDA content; (E) delegated H2O2 content; (F) delegated O
−content. Bars represent the mean ± SE (P < 0.05) of at least three independent experiments.