Figure 5.

Oxidative stress in tomato leaves grown under control or stress combination conditions (salinity + heat, S + H) with (+MEL) or without melatonin pre-treatment. (A) Antioxidant capacity; (B) Hydrogen peroxide (H₂O₂) concentration; (C) Lipid peroxidation measured as malondialdehyde (MDA) content; (D) Protein oxidation measured as carbonyl-groups content and normalized against soluble protein content. Values represent means ± SE (n = 6). Bars with different letters within each panel are significantly different at p < 0.05 according to Tukey’s test.