Both the Republic of South Africa (RSA) and southern Australia have significant areas of environmentally degraded farmlands that are economically marginal for both agriculture and commercial wood production. These lands, a large proportion of which are in low rainfall zones, also suffer significant environmental degradation as a consequence of unsustainable land uses. As a result, in both countries, the economic viability and future prospects of those farming this land - and of the wider rural communities that depend on them - are also marginal.
The greater incorporation of commercial tree growing into the farming enterprise is recognised in both RSA and Australia as an important part of the response to the economic and environmental challenges on these marginal lands. However, in both countries the very restricted suite of tree species and breeds that provide a commercial return on marginal sites imposes a limit on the implementation of this strategy.
Eucalypts are of increasing importance as commercial plantation and farm forestry trees in both countries. However, species and breeds currently available limit commercially viable production to higher-rainfall zones, precluding commercial establishment on most marginal lands. Consequently, in both RSA and Australia, there is strong interest and some preliminary experience in the development of new breeds of pure and hybrid eucalypt species for establishment on marginal lands.
This project aimed to address limitations to reforestation on lands marginal for agriculture and commercial wood production and thus assist the transformation of the farm and landscape necessary to improve economic and environmental conditions. It built on initial work that established the foundations for developing genetically improved Eucalyptus (including Corymbia) pure and hybrid species.
The research team undertook the following activities in order to provide farmers on marginal lands in the medium rainfall zone (~500-700 mm annual rainfall) of southern and eastern RSA and south-eastern Australia with pure and hybrid eucalypt species suitable for commercial wood production:
They assembled appropriate genetic resources of nominated pure eucalypt species and hybrid combinations, developed a better understanding of the reproductive biology of the species involved and created new hybrid combinations, at both species and provenance levels. They also gained greater knowledge of the propagation characteristics and technology options for the species and hybrids involved and evaluated hybrid and parental species performance. They sought a better understanding of the basis of hybrid performance in eucalypts, and how this knowledge could be used to develop enhanced (more cost-effective and more reliable) breeding strategies for the generation of eucalypt hybrids. Finally they communicated the new knowledge and technology packages to those representing farmers, the forest industries, and other interested parties.
A review of baseline information on eucalypt hybrids and lesser-known eucalypt species of commercial potential on marginal lands was completed. CSIRO, CSIR and the University of Stellenbosch undertook a program to maintain and expand their clone banks of eucalypt species relevant to the project, to exchange genetic material as agreed, and to undertake crosses between candidate species. The CSIRO undertook a study of the reproductive biology and phenology of flowering in spotted gums to enable comparisons across years and to accommodate the reduced flowering associated with drought conditions at the rainfed stands under study in southern NSW. Additional phenological studies were undertaken in an irrigated clonal seed orchard of Corymbia maculata at Corowa in southern NSW. The phenology of the flowering cycle was confirmed and experimental treatments to identify optimum protocols and timing for controlled pollination, and the level of self-fertliity in the species, were implemented.
Tasks completed included crossing to produce provenance and interspecific hybrids, assessment of vegetative propagation potential and establishment and maintenance of field trials. Trial establishment of hybrids and trial maintenance continued in both countries; the final Australian trials were established in September 2006.
Work continued on development and application of underpinning knowledge about hybridity. Results suggested there was potential for making genetic gains in hybrids using simplified breeding strategies which reduce the time taken to deploy improved germplasm and cost less to implement.
Links:
[1] http://www.aciar.gov.au/country/South Africa
[2] http://www.aciar.gov.au/programarea/Forestry