EXPOSURE OF GRACILARIA TO VARIOUS ENVIRONMENTAL-CONDITIONS .1. THE EFFECT ON GROWTH

The effect of experimental conditions on the growth rates of sporelings and tips of four Gracilaria species has been studied. The hypothesis tested was that exposure to suboptimal environmental conditions might result in increased growth rate under optimal conditions. Sporelings of G. tikvahiae and G. verrucosa did not confirm this hypothesis. However, G. conferta tips and G. domingensis sporelings showed an inverse relationship between indoor (hardening) and outdoor (common garden) growth rates. No single set of abiotic conditions during hardening resulted in optimum growth of all 4 species of Gracilaria during the common garden phase. The difference between the two pairs of species might be a result of their geographical distribution. The first pair has a very wide distribution with a lower optimal temperature, while the second pair is limited to a warm environment.