Silicon Supply through the Subirrigation System Affects Growth of Three Chrysanthemum Cultivars

The effect of silicon (Si) treatment on the growth of three chrysanthemum cultivars grown in a soilless substrate was evaluated. Rooted terminal cuttings of Dendranthema grandiflorum ‘Gaya Pink’, ‘Lemmon Tree’, and ‘White Angel’ were transplanted into pots containing a coir-based substrate. A nutrient solution containing 0, 50, or 100 mg·L−1 Si from potassium silicate was supplied once a day through a subirrigation system. Application of Si significantly increased the plant height, stem diameter, number of branches, and chlorophyll content, as compared to the control. Addition of Si at 50 and 100 mg·L−1 into the nutrient solution significantly enhanced number and size of flowers, respectively. When plants were treated with Si necrotic lesions appeared in the older leaves at the beginning of the flowering stage. Concentrations of phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), and zinc (Zn) in the leaves increased, while the concentrations of potassium (K), boron (B), copper (Cu), iron (Fe), and manganese (Mn) decreased with the increasing Si concentration in the nutrient solution. Among the cultivars, ‘Lemmon Tree’ contained the greatest Si concentration (1364 μg·g−1) followed by ‘Gaya Pink’ (1158 μg·g−1) and ‘White Angel’ (586 μg·g−1).