Eucalyptus badjensis; a potential alternative to temperate commercial eucalypts with selection and breeding

Cele J, Swain T
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Eucalyptus badjensis was identified in ICFR site-species trials as one of the few species with commercial potential in the temperate summer rainfall regions of South Africa. This is because the species has an optimum Mean Annual Temperature (MAT) range between 14.5 °C and 17 °C and is considered as cold tolerant as E. nitens and moderately snow hardy. Eucalyptus badjensis is only slightly less frost hardy than E. macarthurii and E. benthamii, and is as hardy as E. nitens. A breeding programme to investigate provenance and family differences in the species was initiated in 1993 with the establishment of a 1st series of trials (E93/01) at Woodstock, Lothair and Geluk, Paulpietersburg. The breeding population was expanded in 2000 with the establishment of a 2nd E. badjensis trial series (E93/02) planted across three sites, Hlelo and Blesbokspruit in Piet Retief and Claimont, Bulwer, in year 2000.

There were significant growth differences between the five provenances at full rotation; with the Cathcart and Glenbog provenances being the top performing provenances, with Badja being the worst performing provenance at all three sites. Significant differences exist between the best and below average families at all sites. Blesbokspruit and Hlelo showed moderate to high heritabilities for dbh (h2 =0.29 and 0.46, respectively). Several unimproved E. badjensis families performed better than, or equal to, external controls in this trial series. Results from ICFR site-species trials indicated that E. badjensis has promising pulp properties, being second to E. smithii for mean dissolving pulp yield.

Growth and wood property results from the 1st and 2nd trial series confirmed the potential of E. badjensis as a viable alternative to the commercial species currently grown at these sites. The range in variation for growth, basic density, pulp and stem form coupled with moderate to high heritabilities in E. badjensis, indicates that significant gains can be expected from selection and breeding of superior trees in this species.