Callus Induction in Baru (Dipteryx alata Vog.) Explants

Baru (Dipteryx alata Vog.) is a species with great economic and environmental potential; it has popular acceptance, besides being a very productive species. Alternative propagation methods are important for species maintenance and exploration. Thus, micropropagation emerged as an alternative technique, providing genetic stability and the production of a large number of seedlings. The aim of the present investigation was to develop a callus induction protocol for in vitro baru explants. The tested explants were nodal, internodal and foliar segments. The explants were disinfected for 30 seconds in 70% alcohol (v/v) and 2 minutes in sodium hypochlorite (1.25% active chlorine). This was followed by triple washing. The inoculation was carried out in test tubes containing 15 mL MS medium (30 g L-1 sucrose, 6 g L-1 agar and 100 mg L-1 ascorbic acid) supplemented with 2.0 mg L-1 naphthalene acetic acid (NAA). The solution also contained 0.0, 2.5 or 5.0 mg L-1 of 6-benzylaminopurine (BAP) with the pH adjusted to 5.8. In the incubation phase, the explants were cultured for seven days in the dark and then subjected to a photoperiod of 16 hours (43 µmol m-2 s-1) at 25 ± 2 °C. The treatments were studied with 2.5, 5.0, 7.5 or 10.0 mg L-1 BAP additions to the MS. Callus formation, contamination and oxidation evaluations were undertaken. The results obtained when using 2.0 mg L-1 NAA concluded that such a treatment should be used to induce callogenesis from nodal explants, while for the tested baru leaf explants, the best results for callus formation were given by the combination of 2.0 mg L-1 NAA with 2.5 mg L-1 of BAP to.