Note
Comparative growth studies have been made of the red seaweed
Gracilaria tikvahiae and the freshwater macrophytes Eichhornia crassipes
(water hyacinth), Lemna minor (duckweed), and Hydrilla verticillata.
Effects of nutrient concentration, flow rate of water through the
culture system (retention time), and plant density on yield have
been determined for each species. Relationships between wet weight,
dry weight, and ash-free dry weight (organic content) have also been
determined for each species collected from the wild and from cultures,
the latter determined as a function of nutritional conditions of the plants.