The effect of potassium silicate foliar application on the growth and development of marigolds in water deficit conditions

The ornamental plant industry faces many environmental constraints, such as drought due to climate change. Therefore, the use of materials that mitigate these stresses is essential. A pot experiment was conducted to investigate the effect of potassium silicate on the physiological and biochemical responses of marigolds under water stress. Four water deficit treatments were applied, including 90, 80, 70, and 60% of field capacity and potassium silicate at three concentrations (0, 1, and 3 mM). Results showed that the water deficit at 60% FC significantly reduced leaf relative water content (10.6%) and plant vegetative characteristics (height, leaf area, dry weight) compared to 90% of crop capacity in the no foliar spray condition. Increased ion leakage was observed in plants under water stress as an indicator of oxidative damage. In response to oxidative stress caused by a water deficit, the amount of chlorophyll, carbohydrate, and proline increased compared to the control. Foliar spraying of potassium silicate at a dosage of 3 mM increased the amount of chlorophyll a (92%), chlorophyll b (74%), and total chlorophyll (73%) under 60% FC stress compared to the control. The number and diameter of flowers increased by 39% and 16%, respectively, in the 3 mM treatment compared to the plants without foliar spraying. According to the results, foliar spraying with potassium silicate at a concentration of 3 mM reduced the negative effects of drought stress on the growth characteristics of marigold, such as leaf area and dry weight, and increased the amount of essential oil in the plant. In this way, the use of 3 mM potassium silicate before transplanting plants into environmental conditions can prevent damage caused by a water deficit.