Uptake of benzyladenine in explants of <i>Picea abies</i> and <i>Pinus sylvestris</i>

Primary explants of Picea abies (L.) Karst. and Pinus sylvestris L. were incubated for various periods in solutions containing different concentrations of [ 14 C]‐benzyladenine. Time course analysis showed that uptake was linear for the initial 60 min; after this time linear uptake continued but at a much reduced rate. The amount of benzyladenine taken up by the explants saturated at a concentration about one third of that of the medium, Concentration dependence experiments showed that BA uptake was directly proportional to the external concentration. These results and those from experiments in which uptake was examined at different temperatures are consistent with a passive mode of BA uptake. The results are discussed with respect to in vitro micropropagation.