THE INFLUENCE OF DIFFERENT WATER QUALITY ON THE GROWTH OF SOME FOLIAGE PLANTS IN HYDROCULTURE

The experiments have been carried out with the following plant species: Chrysalidocarpus lutescens, Dracaena deremensis 'Warneckii', Dracaena fragrans 'Massangeana', Ficus benjamina and Spathiphyllum floribundum 'Mauna Loa'. The plants were cultivated as pot plants in expanded clay (8 – 16 mm diameter).

Each nutrient solution consisted of differently prepared water (a. tap water, b. water decationized by cation exchange resins, Na⁺-form, c. water decationized by cation exchange resins, H₃O⁺-form, and d. water deionized by cation/anion exchange resins) and a special fertilizer (15 % N, 3.06 % P, 18.3 % K, 3.6 % Mg; 1.0 or 1.5 g/l). The calcium lost by water preparation was replaced by equivalent amounts of calcium as CaSO₄ in the nutrient solution.

The plants were cultivated for about 10 to 12 months. During this period the nutrient solution was renewed regularly and controlled weekly for pH, conductivity, O₂ and NO₃-N. The dry matter of the leaves was analyzed for mineral nutrient contents.

The Spathiphyllum-plants grew best in decationized water (H₃O⁺-form). Dracaena showed high yield and quality when cultivated in tap water or water decationized (Na⁺-form); deionized water and decationized water (H₃O⁺-form) resulted in small plants and reduced their quality. Chrysalidocarpus reacted conversely to Dracaena. Plants of Ficus benjamina showed best development when grown in tap water, followed by deionized and decationized (H₃O⁺-form) water. They did not tolerate the decationized water (Na⁺-form).

The results indicate, that the plant species show a quite different reaction on the water qualities proved during the course of the experiments.