First mini-cutting protocol for Ocotea odorifera (Vell.) Rohwer (canela-sassafrás): Effects of indole-3-butyric acid, seasonal variability, and anatomical features of mini-cuttings on adventitious rooting

Ocotea odorifera (Vell.) Rohwer (Lauraceae), commonly known as canela-sassafrás, is a medicinal tree species native to the Brazilian Atlantic Forest, valued for its essential oils and their wide applications in cosmetics, perfumery, pharmaceuticals, and bioinsecticides. However, both sexual and vegetative propagation of this species are challenging. This study evaluated the rooting potential of O. odorifera mini-cuttings collected in all four seasons of 2023 and treated with five concentrations of indole-3-butyric acid (IBA). In addition, anatomical features associated with adventitious root formation were examined. Mini-cuttings, 5 cm in length and bearing one apical pair of leaves, were obtained from pre-established mini-stumps and subjected to basal immersion in 50% hydroalcoholic IBA solutions (0, 1500, 3000, 4500, and 6000 mg L ^− 1 ) for 10 seconds, followed by 90 days under controlled greenhouse conditions (25 ± 2°C, 85% RH). No significant interaction was observed between season and IBA concentration. The highest rooting percentage (68.2%) occurred at 3000 mg L ^− 1 IBA, whereas the greatest mean number of roots (5.2) and mean root length (5.9 cm) were achieved at 6000 mg L ^− 1 . Spring was the most favorable season, with 90% rooting, 5.4 roots per cutting, 9.3 cm root length, and 50% sprouting. Anatomical analysis revealed root formation from the vascular cambium, with no continuous sclerenchymatous rings acting as physical barriers. For optimal rooting, we recommend collecting mini-cuttings in spring and applying 3000 mg L ^− 1 IBA.