Effects of the Ionic Composition of Nutrient Solutions on the Dry Weight and the Chemical Content of Doritaenopsis

Abstract

Effects of the ionic composition of nutrient solutions on the dry weight and the chemical contents of Doritaenopsis plant potted by sphagnum moss were investigated. Dry weight of shoot, root, inflorescence and these dry weight ratios were relatively constant in different treatment. However, increase of K⁺ levels increased shoot dry weight, while that of Ca²⁺ levels had a reverse effect. Dry weight ratios showed large difference among different organs. The values were 6–7%, 9–10%, and 7–8% in shoot, root, and inflorescence, respectively. Mineral content increased corresponding the increase in mineral ions in the nutrient solution, but the absorption of the other ions were inhibited antagonistically in the same ion group, i.e. in cations or anions. In cationic treatments, significant differences of Ca and P concentrations in the shoot were observed. In anionic treatments, significant differences in P and Ca concentrations in the root and N and Ca concentrations in the inflorescence were observed. These differences indicated that absorption and translocation of each ion was affected by composition of the nutrient solution. K⁺ inhibited H₂PO₄⁻ absorption and the translocation and NO₃⁻ accelerated Ca²⁺ absorption but the mechanism was not clear.