Effect of Foliar Application of Silicon on Physiological Responses of Chrysanthemum (<i>Dendranthema ×grandiflorum) at Two Different Growth Stages

Abstract

To evaluate the physiological responses of chrysanthemum to silicon spray in non-stress conditions, this study was performed in two separate experiments (at 4 to 5 and 8 to 12-leaf stages) as a factorial randomized completely design with two factors: silicon source (in two levels: sodium silicate and calcium silicate) and the concentration of silicate at five levels (0, 50, 100, 150 and 200 mg L^-1) in cocopeat- perlite (1:1 v/v) medium in four replications and two observations. Physiological traits such as catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) activity, proline, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) content were measured. The results showed that the foliar spray of sodium and calcium silicate increased the activity of CAT, APX and GPX enzymes and MDA, but proline and H₂O₂ were decreased. Generally, in the stage of 8-12 leaves, sodium silicate at high concentrations (150 and 200 mg L^-1) was the most effective in increasing antioxidant enzymes activity and reducing proline, MDA and H₂O₂. At 4-5 leaf stage sodium silicate at 100 mg L^-1increased antioxidant enzymes activity and calcium silicate at 150 mg L^-1 reduced proline, MDA and H₂O₂.