Figure 5.

Effect of soil amendment using biochar and K-humate foliar application on the activity of antioxidant-related enzymes of onion plants grown in sodic-saline soil and irrigated regularly (Every 30 days) or stressed with deficit irrigation (every 45 days) during 2018/2019 and 2019/2020 seasons. (A) Superoxide dismutase (Units mg⁻¹ protein), (B) Catalase (Units mg⁻¹ protein), and (C) Peroxidase (Units mg⁻¹ protein). Data presented are the means ± standard deviation (mean ± SD) of three biological replicates. Different letters signify statistically significant differences between treatments according to Tukey’s HSD test (p_{irrigation×treatment} ≤ 0.05).