VITRO OF Melanoxylon brauna SCHOTT. MORPHOGENESIS: RESPONSIVENESS OF EXPLANTS TO PERMANENT AND TEMPORARY IMMERSION GROWTH REGULATORS

Abstract

ABSTRACT Melanoxylon brauna is propagated by seeds, however, low yield, pest attack and short viability are problems in seedling production. In vitro cultivation is an alternative for large-scale seedling production, but studies with this species are scarce. The aim of the work was to analyze the in vitro morphogenesis of brauna. Explants after induction of growth regulators. Three experiments were performed: I. In vitro bud proliferation of juvenile explants at different BAP concentrations. Was analyzed the number and length of shoots (mm); bud explants-1 (%); calogenesis (%) and direct and indirect organogenesis budding-1 (%). II. In vitro rhizogenesis of shoots with different types and auxin concentrations. III. In vitro rhizogenesis of under temporary immersion of shoots at different IBA concentrations. It was analyzed in experiment I and II: calogenesis (%); rhizogenesis (%); number, length (mm) and root dry mass (mg) the shoots. The nodal segment with two axillary buds was the most responsive explant regardless of the use of BAP. The stem apex with the use of BAP (2.5-3.5 mg.L-1) was the most responsive in the proliferation of shoots. Tested concentrations of auxins IBA, NAA and 2,4-D were not sufficient for in vitro rhizogenesis. The average of the maximum technical efficiencies of the variables used to analyze rhizogenic process suggests the treatment of the shoots base by temporary immersion in the IBA at an approximate concentration of 2,500 mg.L-1 and planting on the vermiculite substrate.