Silicon-Induced Modulation of Photosynthetic Pigments, Osmolytes, and Phytohormonal Regulation Boosted the Drought Tolerance in Elymus sibiricus L

Plants face various environmental stresses during their life cycle that are crucial in defining plant stress responses. Among them, drought majorly affects the growth, physiological mechanisms, and yield of crops. Therefore, the present study investigated potential role of silicon (Si) in reducing the impacts of drought in Elymus sibiricus (L.). The Si was applied as seed priming at 50, 100, 150, and 200 mg L −1 under well-watered (normal) and drought-stressed (45% water-holding capacity) conditions. Drought stress decreased the Chl a by 61.6%, Chl b by 59.4%, total Chl by 60.9%, and RWC by 51.1% and caused oxidative damage by increasing electrolyte leakage by 595.4%, malondialdehyde content by 259.2%, and hydrogen peroxide by 200.4% over the well-watered (CK) condition. However, Si positively affected the growth and other traits under normal and drought conditions. The Si at 150 and 200 mg L −1 enhanced the total soluble proteins by 97.6 and 120%, soluble sugar by 193 and 245.9%, proline by 212.7 and 273.8%, SOD by 40.5 and 48.9%, CAT by 150.6 and 127.1%, POD by 87.5 and 121.6%, and APX by 183 and 210.7% over the (CK) under drought-stressed condition, respectively. Furthermore, 200 mg L −1 Si significantly increased the IAA, GA, CTK, and BR and decreased the ABA under drought conditions. Thus, Si at higher levels improved the tolerance of the Elymus plant against drought. Overall, the present study suggests the Si-mediated amelioration of drought stress in Elymus that could be used to enhance drought tolerance in other forages and crop plants.