Micropropagação de dois genótipos de Sequoia sempervirens com adição de pequenas concentrações de cinetina

Sequoia sempervirens (D. Don) Endl. is a conifer which produces high-quality wood with potential industrial applications. However, the species shows low germination rates. This study was devoted to optimizing a protocol for shoot multiplication of S. sempervirens through micropropagation. Two genotypes, adapted to southern Brazil, constituted the source of explants for consecutive experiments aiming in vitro multiplication. We used the traditional MS (Murashige & Skoog) culture medium at 50% of its original concentration, supplemented with plant growth regulators under two approaches. For multiplication we combined α-naphtalene acetic acid (NAA) and 6-benzilaminopurine (BAP) at distinct concentrations. In the second experiment, we tested concentrations of three cytokinins types (BAP, kinetin  and 2-isopentheiladenine ). NAA at 0.1 mg L -1 enabled the production of shoots with higher mean length for the main branch. The use of kinetin in low concentrations provided the best performance for shoot multiplication, differing between two genotypes. We outline a recommendation of the most suitable plant growth regulators and their concentration for shoot multiplication of S. sempervirens , which might assist further work aiming at adventitious rooting and acclimatization.