A bicarbonate-containing medium for the solution culture of submersed plants

Abstract

A bicarbonate-buffered hard-water medium was evaluated for the solution (nonrooted) culture of submersed aquatic plants. The new medium had an initial pH of 8.2, and after 2 weeks of plant growth in it, pH values remained similar to those in hard-water lakes. Several plants from hard-water lakes grew more rapidly in the new medium than in the commonly used Gerloff medium. When cultures were aerated with air, Myriophyllum spicatum growth was nearly twice as great in the new medium as in Gerloff medium, and growth of Vallisneria americana and Elodea canadensis in the new medium was 4 and 13 times that in Gerloff medium, respectively. When both cultures were aerated with 1% CO2, growth rates of M. spicatum and E. canadensis in the new medium were not distinguishable from those in Gerloff medium, but the growth of V. americana was 40% greater in the new medium. Myriophyllum spicatum was much less susceptible to attack by the fungal pathogen Colletotrichum gloeosporioides in the new medium than in Gerloff medium, similar to the susceptibility shown in nutrient-amended lake water. Key words: aquatic plants, culture techniques, plant pathogens.