LAUSR

This study aimed to evaluate cytokinin influence during in vitro multiplication stage and activated charcoal in combination with indole-3-butyric acid (IBA) during in vitro rooting of Handroanthus impetiginosus . For in vitro multiplication, nodal segments of shoots obtained from in vitro seedlings establishment were inoculated in Woody Plant Medium (WPM), with and without the following concentrations of 6-benzylaminopurine (BAP), kinetin (KIN) and thidiazuron (TDZ): 0.5; 1.0; 2.0; 4.0 and 8.0 µmol L -1 . For in vitro rooting, shoots were inoculated in WPM containing combinations among IBA (1.0; 3.0; 6.0 and 9.0 μmol L -1 ) and activated charcoal (1.0; 2.0 and 3.0 g L -1 ), as well as their absence within culture medium. The highest number of shoots and buds was reached after using TDZ 8.0 μmol L -1 , where in the best rooting occurred after adding activated charcoal 2.0 g L -1 , regardless of IBA concentration. Our results show that using TDZ in a suitable level for in vitro multiplication stage followed by using 2.0 g L -1 of activated charcoal to obtain well rooted shoots is efficient for ipe-roxo micropropagation in a low cost-manner and quickly, besides providing knowledge about how to keep this threatened extinction species in an in vitro environment, which may help other conservation studies.