Fig. 4

Comparison of the impact of salicylic acid (SA), potassium nitrate (KNO3), and a control for superoxide anion (O–2) and hydrogen peroxide (H2O2) (A), catalase (CAT) and superoxide dismutase (SOD) enzyme activities (B), peroxidase (POD) and ascorbate peroxidase (APX) enzyme activities (C), total protein and proline content (D), electrolyte leakage (E), and total phenolic content (F) in the leaves of potato cv. Sutlej. The bars represent the standard error (±) of the mean (n = 4). Lettering indicates the differences in the treatment means that was conducted through the least significant difference (LSD) test at P ≤ 0.05 after analysis of variance.