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

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-1 increased antioxidant enzymes activity and calcium silicate at 150 mg L-1 reduced proline, MDA and H2O2.