Esterilização química e mixotrofismo na micropropagação de matrizes adultas de Corymbia maculata Hill & Johnson

Abstract

The Corymbia genus stands out for having species resistant to abiotic and biotic stresses, and high density of wood, ideal for sawmills, sleepers, posts, posts, heavy constructions, firewood and coal. Due to the expansion of plantations to unconventional areas and the quest to improve the final raw material, hybrid combinations have expanded. However, most of these species have difficulty in adventitious rooting by cuttings and/or mini-cuttings, mainly in the case of adult vegetative material. In this sense, the purpose of this proposal is to improve the procedures for tissue culture of Corymbia maculata, by rescuing adult matrices and by defining a micropropagation protocol, with potential for application in breeding programs. For the multiplication of axillary buds, nodal segments from the in vitro establishment of two adult matrices were used, where concentrations of active chlorine [0.000%; 0.001%; 0.003% and 0.005% (v/v)] and two concentrations of BAP (0.5 mg L-1 and 1.0 mg L-1). The number of buds emitted, chlorosis, oxidation and fungal contamination were evaluated at the end of each subculture. For Elongation phase, concentrations of active chlorine [0.000%; 0.001%; 0.003% and 0.005% (v/v)] and two concentrations of NAA (0.5 mg L-1 and 1.0 mg L-1), in addition to three gas exchanges (mixotrophism). At 60 days, oxidation, vigor, shoots length, average number of shoots per explant; photosynthetic pigments and leaf anatomy were evaluated. In rooting, a pretreatment was performed, using culture medium supplemented with 5 mg L-1 of IBA, after three days of inoculation, the shoots were transferred to a new treatment. This new treatment was conducted in a completely randomized design, in a factorial arrangement (3×2×2), testing three times of exposure to IBA (0, 24 and 48 hours), luminosity (presence and absence of light) and two concentrations of charcoal activated (absence and 100 mg L-1). Twenty shoots were used by repetition. After 45 days of adventitious rooting induction, the percentage of survival and rooting were evaluated, in addition to the vigor, oxidation and root anatomy. The in vitro multiplication of axillary buds was better when using a reduced concentration of active chlorine [0.001% (v/v)] combined with 0.50 mg L-1 of BAP and / or 0.05 mg L-1 of NAA. Elongated shoots depend on the absence of active chlorine, and supplementation of the culture medium with 0.5 mg L-1 of NAA and 0.05 mg L-1 of BAP, and three porous membranes. In vitro rooting showed a low percentage (±5.08%), with the absence of luminosity and activated carbon being recommended. The roots formed were vigorous and showed a connection with the vascular cambium.