Potassium silicate enhances drought tolerance of Bellis perennis by improving antioxidant activity and osmotic regulators

Ornamental plants can usually encounter various types of environmental stress, which reduce plant productivity. A proper application of fertilizers can improve plantsʼ tolerance to drought stress. Nutrients such as potassium and silicon are known to have beneficial effects. This study aimed to evaluate the growth of Bellis perennis under drought stress (80, 70, and 60% FC) and with the application of potassium silicate (0, 2, and 4 mM). The results showed that potassium silicate (2 and 4 mM) increased K and Si accumulation in plants under drought stress. Plants treated with potassium silicate under drought stress exhibited a lower degree of electrolyte leakage and less MDA accumulation in the following order: 2 and 4 mM potassium silicate. An increase in relative water content and chlorophyll was observed with application of potassium silicate under drought stress. Regardless of potassium silicate, the plant enzymatic defense system was significantly improved compared to non-stressed plants. Potassium silicate enhanced the amount of osmotic regulators (carbohydrate and proline) and secondary metabolites (flavonoids and phenols) compared to control plants regardless of drought stress. The anthocyanin content in the flowers significantly decreased by 32.2% when the plants were treated with 4 mM potassium silicate at 60% FC, compared to 80% FC. In conclusion, potassium silicate mitigated the effects of drought stress, enhanced plant tolerance to drought stress, increased the activity of antioxidant enzymes, and improved the amounts of osmotic regulators and secondary metabolites.