Studies on the hormonal relationships of algae in pure culture : II. The effect of potential precursors of indole-3-acetic acid on the growth of several freshwater blue-green algae.

The effect of potential precursors of Indole-3-acetic acid (IAA) on the growth (increase in dry weight) of Anacystis nidulans, Chlorogloea fritschii, Phormidium foveolarum, Nostoc muscorum and Tolypothrix tenuis have been in vestigated under as sterile conditions as possible. Tryptamine showed a marked stimulation of growth indicating its possible conversion to IAA. Tryptophan at a hormonal concentration promoted growth in only 1 species, Chlorogloea fritschii. Indole stimulated the growth of Chlorogloea fritschii, Nostoc muscorum and Tolypothrix tenuis. Anthranilic acid promoted the growth of Nostoc muscorum, it failed to stimulate the growth of Chlorogloea fritschii. Anthranilonitrile promoted the growth of Nostoc muscorum and Chlorogloea fritschii. ^-Alanine promoted the growth of Nostoc muscorum, Tolypothrix tenuis and Chloro gloea fritschii at hormonal concentrations.