Silicon Stimulates Physiochemical Properties of Coriander (Coriandrum sativum L.) to Improve Growth and Yield under Salt Stress

Silicon (Si) has a principal role in mitigating the adverse effects of salt stress on plant growth; however, its effects on physiochemical properties of medicinal plants under salinity is still unknown. This study investigated the effect of Si and salinity on growth, chlorophyll and water content, the antioxidant capacity of coriander (Coriandrum sativum L.) leaves as factorial in a randomized complete block design (RCBD). Foliar application of 50, 100, and 200 mg/L Si and 50, 100, and 200 mM NaCl were applied on 4-leaf plants. The results revealed reduced growth by representing lower shoot and root dry weight through progressing the salinity. 100 and 200 mg/L Si represented a greater role in alleviating the salinity stress on growth properties. Salinity significantly reduced chlorophyll (Chl) and relative water content (RWC), but they were improved by Si spraying. Total phenol content (TPC) and total flavonoid content (TFC) significantly increased up to 100 mM NaCl and then decreased at 200 mM NaCl. Salinity led to increases in catalase (CAT) and superoxide dismutase (SOD) activity, but higher Si concentration reduced them. 100 mg/L Si and 100 mM NaCl was the best treatment for obtaining the optimum essential oil (EO) percentage and yield. Finally, 100 mg/L Si can be suggested to promote the plant growth and yield by changing physiochemical characteristics under medium or severe salinity.