Effect of gibberellin and kinetin on the regeneration ability ofFucus vesiculosus L.

The influence of gibberellic acid (GA 3 ) and kinetin (6-furfurylaminopurine) on the regeneration ability of the basal and apical thallus fragments of Fucus vesiculosus L. was examined. The naturally occurring gibberellin and kinetin-like substances in these thallus fragments were also studied. It was found that exogenously applied GA 3 markedly increased the number of adventitious branches formed on the cut surface of the thallus fragments taken from the apical parts of plants. The concentration of 0.001 mg GA 3 I-1 proved to be the most effective. The growth promoting effect of GA 3 was increased by simultaneous action with kinetin. In experiments in which the fragments of the basal parts of the thallus were treated with GA 3 , as a rule a slight growth inhibition was observed. The growth responses of the investigated plant tissues to gibberellin and kinetin varied according to season. Usually their susceptibility to the applied plant hormones was greater in spring than is summer. The shifts in growth reaction were related to the seasonal changes in the content of endogenous gibberellin and kinetin-like substances in the investigated parts of the thallus. It is suggested that growth regulators of the gibberellin and cytokinin type are involved in the regeneration processes in Fucus.