Mini-cutting protocol and anatomical basis of adventitious rooting in Ocotea odorifera

Ocotea odorifera (Vell.) Rohwer (Lauraceae), commonly known as canela-sassafrás, is a tree species native to the Atlantic Forest and valued for its essential oils used in cosmetics, pharmaceuticals, and bioinsecticides. Developing an efficient mini-cutting protocol is fundamental for conservation efforts, as it provides a viable alternative for producing seedlings of this threatened species. This study evaluated the rooting of mini-cuttings collected during the four seasons of 2023 and treated with five concentrations of indole-3-butyric acid (IBA), and investigated anatomical features associated with adventitious root formation. The experiment followed a completely randomized design in a 4 × 5 factorial arrangement, with four replications of ten mini-cuttings per experimental unit. Mini-cuttings, five centimeters in length and containing a pair of apical leaves, were obtained from established mini-stock plants and subjected to basal immersion in hydroalcoholic IBA solutions (0, 1500, 3000, 4500, and 6000 mg L⁻¹) for ten seconds, followed by ninety days in a greenhouse under 25 ± 2 °C and 85% RH. No significant interaction was observed between season and IBA concentration. The highest rooting percentage (68.2%) occurred with 3000 mg L⁻¹ IBA, whereas 6000 mg L⁻¹ resulted in a greater mean number of roots and greater root length. Spring exhibited the best overall performance, with ninety percent rooting. Anatomical analysis revealed that roots originated from the vascular cambium. Based on these findings, we recommend collecting mini-cuttings in spring and applying 3000 mg L⁻¹ IBA.