Effects of silicon on some phytochemical traits of purple coneflower (Echinacea purpurea L.) under salinity

Silicon is the second most abundant element present in the earth's crust following the oxygen. Although it is not considered as an essential element for plant growth, some studies have suggested that silicon application significantly increases plant growth under salinity conditions. In order to investigate the effect of salinity stress and silicon on some phytochemical traits of purple coneflower (Echinacea purpurea L.), a pot experiment was conducted in a factorial-based completely randomized design with four salinity levels and four silicon concentrations with four replications. The measured traits include antioxidant activity of aerial parts, root and shoot proline, total flavonoid and phenol in shoot, caffeic acid concentration in aerial parts and root, and chlorogenic acids in root and shoot. The results showed that the interaction of salinity and silicon was significant for all traits except for the antioxidant activity of the shoot. Salinity stress significantly affected the chlorogenic acid content of the root. The effect of salinity on the caffeic acid content of root was significant at 1%, however, it did not affect the amount of caffeic acid in the shoot. The interaction of salinity and silicon on caffeic acid content of root was significant at 5% suggesting that silicon can reduce the negative effects of salt stress on the purple coneflower.