XVI International Botanical Congess

Comparative studies on phytohormones of Black Sea algae of the orders Gigartinales, Ulvales and Fucales considerable different in their structure, morphology and type of reproduction, made it possible to establish some differences in the qualitative composition of all investigated growth substances. Maximum concentrations of IAA were found in species of Fucales, which were characterized by the presence of active growth zones. Brown algae showed a high cytokinin activity. Green and brown algae by a greater, as compared to red algae, activity of gibberellin-like substances. Increase in ABA content in brown and green algae during their transition from a vegetative growth to a reproductive development was shown. Seasonal changes in the phytohormonal content in red, brown and green algae were observed: those changes correlated with the periodity of algal growth, development and reproduction.