Micropropagation of Eucalyptus cloeziana mature trees

Abstract

Eucalyptus cloeziana is a species of great commercial interest due to the technical characteristics of its wood. However, the expansion of areas planted is limited by difficulties encountered with its clonal propagation. The objective of this study was to develop a method for cloning select adult trees of this species by a micropropagation technique. Epicormic shoots were induced in branches of adult trees and were viable as explants for in vitro establishment. Shoots were multiplied in vitro using Woody Plant Medium (WPM) culture supplemented with 6-benzylaminopurine (BA) and α-naphthaleneacetic acid (NAA) growth regulators. The optimum concentration of these for promoting proliferation of shoots was genotype-dependent. The best multiplication results were obtained with BA concentrations greater than 0.60 mg L–1 combined with 0.10 mg L–1 NAA for adult tree genotypes numbered 03 and 13, while for tree 05 the optimal result was found for the shoots cultured in culture medium free of the growth regulator NAA. In vitro shoot elongation it was obtained in WPM supplemented with 0.1 mg L–1 BA; a pulse treatment with gibberellic acid (GA3) was found to be of no value. The ex vitro rooting and acclimatisation of micro-cuttings were successful in mini-incubators—adventitious roots formed directly on explants, providing propagules to establish a clonal micro-garden of E. cloeziana select adult trees.