Competência ao enraizamento adventício de miniestacas de Acacia mearnsii De Wild.

Abstract

Acacia mearnsii is a tree species belonging to the Fabaceae family, originally in Australia. The species has great industrial potential for products, such as charcoal and cellulose. It is cultivated in Brazil, mainly in Rio Grande do Sul, for the production of wood and extraction of tannin from its bark. Although it is relevant to the industrial sector, few studies have been carried out with vegetative propagation techniques, with no defined protocol for the utilization of mini-cuttings. Proper management of mini-cuttings can maximize the gains from the genetic improvement of A. mearnsii. Thus, the aim of this study was to study the rooting of A. mearnsii mini-cuttings for vegetative propagation. Rooting was evaluated after 30 days in a humidity chamber through the percentage of survival and rooting, and number and length of the three largest roots. Four experiments were conducted with three clones of A. mearnsii, to evaluate the effect of nutrient solution concentrations (25, 50 and 75% of the standard solution), the type of propagule (apical, one bud and two-bud mini-cuttings), and concentration of indolbutyric acid (IBA) (0; 1,000; 2,000; 3,000 and 4,000 mg L-1) and the time of the year on the productivity and rooting of mini-cuttings. Type of propagule and IBA concentrations in the rooting competence of mini-cuttings were also evaluated in 650 genotypes of 13 progenies. The 75% concentration of the nutrient solution maximized mini-cuttings production. Apical and two-bud mini-cuttings collected during the winter and treated with 2000 mg L-1 of IBA maximize rooting potential of mini-cuttings of A. mearnsii clones. A. mearnsii can be propagated by mini-cuttings from apical and one-bud mini-cuttings treated with 2,000 mg L-1 of IBA.