Plant production of Ocotea odorifera (Vell.) Rohwer by the micro-propagation technique

Abstract

Due to the intense exploitation of its essential oil over the years, Ocotea odorifera was included in the endangered species in Brazil. In this context, the micro-propagation technique is an alternative to sexual propagation, and consequently, it favors the conservation of the species. Thus, the objective of this study was to produce seedlings of O. odorifera through the micro-propagation technique. Seed collection was carried out in mother trees distributed in a natural stand. In vitro cultivation was divided into three phases: (i) in vitro germination and establishment; (ii) elongation and rooting and (iii) acclimatization. For explant disinfestation, a 3x2 factorial was used: three sources of propagules (seed, embryo and nodal segment) combined with two immersion times in NaClO (50%) (5 and 10 min), totaling 6 treatments. In the in vitro establishment, two culture media (MS supplemented with ANA and BAP) combined with or without the addition of activated charcoal were tested. In the elongation and rooting phase, the presence and absence of activated charcoal in the development of shoots was evaluated. For the acclimatization of seedlings and shoots, two ex vitro conditions were evaluated: in a growth room environment and in a nursery. We found significant differences between the evaluated treatments. The embryo-type propagule source and disinfested with 50% NaClO for 10 minutes showed the best morphological characteristics of germination and development. The addition of charcoal to basic MS medium, and free from plant regulators, reduced tissue oxidation in the elongation and rooting phase. Shoots of Ocotea odorifera developed in vitro and adapted well to ex vitro acclimatization conditions. Therefore, the micro-propagation protocol used in this work was efficient, providing the production of healthy and suitable seedlings for field conditions.