CCC and Amo.1618, at relatively high concentrations only, inhibited the
growth of excised branch apices of the red alga Hypnea musciformis. Neither GA3 nor
GA7 stimulated growth of the alga in the presence or absence of these compounds, and
gibberellin-like material extracted from H. musciformis also failed to stimulate
growth. However, both gibberellins stimulated the growth of slow-growing, but not
fast-growing, branch apices of the related red alga Gracilaria verucosa. It is concluded
that endogenous gibberellins may not regulate the growth of H. musciformis, but
this is likely to be a peculiarity of this species and not a general phenomenon in red
algae.
Studies on the Regulation of Algal Growth by Gibberellin