Genetic gains in oil yields after nine years of breeding Melaleuca alternifolia (Myrtaceae)
J. C. Doran A D , G. R. Baker B , E. R. Williams C and I. A. Southwell BA Ensis, PO Box E4008, Kingston, ACT 2604, Australia.
B Wollongbar Agricultural Institute, Wollongbar NSW 2477, Australia.
C 30 Hopkins Street, Weston, ACT 261, Australia.
D Corresponding author. Email: john.doran@ensisjv.com
Australian Journal of Experimental Agriculture 46(11) 1521-1527 https://doi.org/10.1071/EA05205
Submitted: 4 August 2005 Accepted: 2 March 2006 Published: 9 October 2006
Abstract
A breeding program to enhance the economics of producing essential oil (Australian tea tree oil) from Melaleuca alternifolia plantations in eastern Australia by improving oil yields and oil quality commenced in 1993. This paper reports the results of the first (2003) and second harvests (2004) of a yield trial established by the program in 2002. The trial compares the performance of three grades of seed (clonal seed orchard, first generation seedling seed orchard and selected provenance) released to the industry by the breeding program against an unimproved seedlot (industry standard). Industry standard is representative of seed available to growers in 2001 from alternative sources within the industry. Progeny from the clonal seed orchard had the highest oil yield, giving an estimated average improvement in yield over industry standard of 83%. This was followed by selected provenance and first generation seedling seed orchard with 55% and 43% improvement, respectively. These yield improvements were accompanied by desirable changes in oil quality traits among breeding program seedlots which gave lower 1,8-cineole and higher terpinen-4-ol levels than industry standard. Economic analyses have demonstrated that, with current prices less than $20 per kg of oil, older plantations need to be replanted with new germplasm that will yield 90% more oil per hectare than plantings based on unselected seed if they are to deliver a 10% rate of return on investment. Gains of this magnitude are possible through the use of the breeding program’s clonal seed orchard seedlot. If the price drops further, then even greater yield gains will be necessary for farms to remain profitable. These gains will be delivered by the breeding program in the coming years through the release of seed from a second generation seedling seed orchard and fully tested clones suitable for mass propagation.
Additional keywords: breeding strategy, tree improvement.
Acknowledgments
Mr Peter Rose, a tea tree grower and ATTIA member, provided the land and maintained the Codrington yield trial. RIRDC, ATTIA, NSW DPI and Ensis (formerly CSIRO Forestry and Forest Products) provided funding support and institution support came from NSW DPI. We are especially grateful to fellow members of the tea tree breeding committee who help guide the program, namely Richard Davis (representing ATTIA & committee Chair), Robert Tillman (ATTIA), Craig Chapman (ATTIA), Roslyn Prinsley (RIRDC) and recent past members in Richard Spurway (NSW Ag) and Bob Overgaard (ATTIA). Technical support in planting and assessing the trees was provided by Robert Lowe, Michael Russell and John Perin. Kron Aken prepared Fig. 1. Ken Eldridge, Penny Butcher and Paul Macdonell provided helpful comments on early drafts of this paper.
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