Figure 6

Diagram of the hypothesis of how exogenously applied Si and SA alleviate alkaline stress tolerance in tomato plants. Alkaline stress reduces plant growth by enhancing ROS, reducing nutrients uptake due to high-pH and aggravating Na⁺ toxicity. Exogenously applied Si and SA enhance the activation of the antioxidant defence system, modulate key hormones and increase the K⁺ concentration, that eventually helps the tomato plants to survive alkaline stress. Furthermore, the plasma membrane H⁺-ATPase (as per the high expression of LHA1 and LHA2) pumps out H⁺ to the rhizosphere, reducing the rhizosphere pH and enhancing the nutrients uptake.