Genotypic-unspecific protocols for the commercial micropropagation of Eucalyptus grandis x nitens and E. grandis x urophylla

Clones of Eucalyptus grandis x nitens and E. grandis x urophylla were subjected to various culture conditions at every culture stage leading to plantlet regeneration directly from axillary buds. The objective was to determine the possibility of using the same protocol for all clones. Although genotypic effects were evident, generally most clones responded similarly to the tested variations in each of the protocol stages, i.e. bud break, multiplication, and rooting. Estimated yields for the clones of one of the tested E. grandis x nitens hybrids ranged from 24 to 90 acclimatised plants per explant, but those of a natural hybrid were much lower (8 to 15 plants). The tested clones of E. grandis x urophylla produced approximately 10 to 27 plants per explant. It is suggested that such an all-purpose protocol has applications in a commercial environment, such as the production of hedge plants and retrieval from in vitro storage, when large numbers of plants are not required. This would save time, labour, and other costs as compared with having to develop and implement clone-specific protocols.