Effect salicylic acid and silicon on physiological and phytochemical indices of Scrophularia striata L. under water stress

Abstract Water stress, a main factor, exerts influence on the physiological and phytochemical responses of plants. Therefore, to scrutinize the physiological and biochemical reactions of Scrophularia striata under drought stress, a factorial experiment was conducted employing a completely randomized design with three replications plants were subjected to varying concentrations of salicylic acid (0 and 100 PPM), silicon (0 and 1 g/L), and drought stress at two levels (50 and 100% of field capacity) within greenhouse conditions. Data analysis results revealed that drought stress leads to an increase in Ca⁺² and Na⁺ levels in Ilam ecotype under the FC50% treatment. Additionally, Mg⁺² levels in Ilam ecotype, under the control × SA treatment, exhibit an augmentation in comparison to the stress treatment. The application of silicon resulted in an elevation of potassium in Abadanan ecotype under the FC50% treatment. Simultaneous utilization of SA and Si would demonstrate an increased K⁺/Na⁺ ratio in Ilam ecotype within the control × SA × Si treatment. Nitrate levels exhibit an increase in Ilam ecotype under the FC50% × SA × Si treatment. The analysis of amino acid compounds in the tested samples showed that drought stress increased Tryptophan in Ilam ecotype in the FC50% treatment, using SA increased Tryptophan, Phenylalanine and using Si increased Argenine and Valine. 45volatile compounds were identified for the first time in the stem of S. striata by technique (GC-MS). In general, the results the simultaneous use of these two compounds can play an effective role in modulating drought stress in S. striata.