ESTABLISHMENT AND IN VITRO MULTIPLICATION OF Luehea divaricata MART. et ZUCC.

<p><em>Luehea divaricata </em>Mart. et Zucc. (acoita-cavalo) of the Malvaceae family, is a forest-tree species that has suffered great anthropic disturbance during the last decades. This fact has contributed to the reduction of natural populations and, consequently, of its genetic variability. This justifies studies related to the propagation of the species. As a means of vegetative propagation, micropropagation is an alternative for the regeneration of plants with difficult natural regeneration and a strategy for species conservation. The objectives of this study were to determine the most efficient type of explant and growth medium for <em>in vitro</em> establishment and verify the influence of different concentrations of BAP cytokinin in the multiplication of nodal segments of <em>Luehea divaricata</em>. The seeds used were collected and stored by the Fundação Estadual de Pesquisa Agropecuária – FEPAGRO/Florestas (Agriculture and Cattle Research State Foundation – FEPAGRO/Forests), in Santa Maria, RS, Brazil, and the seedlings obtained <em>in vitro</em> were used as sources of the explants. In the selection of the explants and growth medium, the tips of stems and nodal segments grown in the MS and WMP nutritive media were tested. Different concentrations of BAP (0, 5, 10 and 15 mg L^-1) were evaluated in the <em>in vitro </em>multiplication of the species. In the <em>in vitro</em> establishment of <em>Luehea divaricata</em>, both tips of stems and nodal segments can be used and also both growth media. To maximize the growth of the species, the WPM growth medium should be used due to its reduced cost. In the <em>in vitro</em> multiplication of the species, cytokinin BAP should not be added because, besides reducing the costs in the <em>in vitro</em> cultivation of <em>Luehea divaricata</em>, the best response for the majority of the characteristics evaluated was observed in the absence of this regulator,.