Breeding to enhance productivity of plantations of melaleucas for essential oil production in Indonesia

• NSW Agriculture, Australia
• Centre for Forest Biotechnology and Tree Improvement, Indonesia

Cajuput oil, based on foliar essential oils from Melaleuca cajuputi, is popular throughout Asia as an antiseptic and medicine. Oil extraction is an important source of employment in Java, but the plantations on which the industry depends are in need of replacement. This ACIAR small project built on two earlier small non-ACIAR projects.
The first, supported by the Collaboration on Science and Technology Australia-Indonesia (COSTAI), allowed collection of seed of M. cajuputi ssp. cajuputi in the natural stands on the Maluku islands and in northwestern Australia. This seed was used to plant a limited breeding population at Paliyan near Yogyakarta. The second, supported by AusAID's Government Sector Linkages Program (GSLP) for Indonesia, allowed further seed collections in Maluku and on Java and preparation of a breeding strategy.

This project aimed to complete the earler research work by refining and implementing a breeding program for M. cajaputi ssp. cajuputi in Indonesia.

The first priority was to screen trees at Paliyan for their oil and growth characteristics and turn the breeding population into a seedling seed orchard. The scientists tested oil composition, comparing gas chromatography readings with those from near infrared spectroscopy (NIRS) to determine if NIRS was a suitable means of characterising melaleuca oils. They characterised the oil composition of seed orchard material using gas chromatography, and tested the substance paclobutrazol as a promoter of flowering.
An additional objective was institution building at the Centre of Forest Biotechnology and Tree Improvement (CFBTI). Establishing a gas chromatograph and oil extractory at the Centre and training scientists and technicians in their use raised the Centre's capacity to carry out future oil analyses for selection of superior genotypes of M. cajuputi and development of seed orchards.
They also tested the viability of composting leaves after oil extraction to produce organic fertiliser. A by-product of oil distillation is tonnes of inert biomass (leaves and twigs from the stills) in excess to that required for firing the factory boilers. A study undertaken at CFBTI under this project composted this biomass, added it to mounded paddy soil as an organic fertilizer and then observed its effects on yields of four crop plants (tomato, peanuts, maize and chilli). It was also added to nursery potting mix to determine if it was beneficial to the growth of two tree species.

Implementation of the breeding strategy for improving oil yields and oil qualities of M. cajuputi commenced with the start of this project in January 2001. Breeding trees is a long term undertaking and two years is insufficient time to produce the highly improved seed that will ultimately be the product of project seed orchards and to test the impacts of its use.
All stakeholders in the project are awaiting the availability of commercial quantities of seed from the seed orchard. No impediments to adoption of the improved seed are envisaged, as it will be the preferred seed source for all future plantings of M. cajuputi on Java once it is readily available. The new orchards are expected to produce their first seed crops in 2004 and substantial crops from 2006 onwards.
Scientists therefore can only take an educated guess at impacts, based on data when available from project trials and on melaleuca tree improvement work elsewhere. They have predicted gains of up to 20% in growth traits and 20% in oil concentration. These estimates are consistent with gains recorded in a tea tree oil (M. alternifolia) improvement project in Australia.
Comparison of these figures with current average production figures for M. cajuputi in Indonesia lead to prediction of oil yield increases from 62 to 86 kg per hectare - an improvement of A$240 per hectare at the distillery gate. In addition worthwhile improvements in oil quality would ensure that all of the production meets the minimum Grade A standard of 55% 1,8-cineole. Even greater yield improvements can be predicted once the larger project seed orchards are thinned and start producing seed in a few years time.
In the study of composted spent biomass scientists found that its addition to soil enhanced plant growth and led to significant improvement in crop yields. Thus it holds promise as a soil improver and after further development may be an additional product out of the oil industry.