Genetic gain in oil productivity from breeding program of Cajuput (Melaleuca cajuputi subsp. cajuputi) in Indonesia

Abstract

A long-term breeding program of cajuput (Melaleuca cajuputi subsp. cajuputi) in Indonesia has aimed to increase oil productivity and quality through imposing selection for oil yield and 1,8-cineole content. This study examined the realized genetic gain for the two key variables of oil yield, oil concentration and leaf biomass. Data were collected from a trial based on seeds collected from two unimproved, and two improved sources with selection intensities (IS) of 1.1 (10% of trees selected) and > 2.5 (<1% of trees selected). The trial was laid-out in a randomized complete block design with five replications. It was measured at 10 years of age. The leaf oil concentration of the IS >2.5 seed source was significantly higher than for the other sources; a realized genetic gain ranging from 14% to 31%. However, although not significant, this seed source had the lowest leaf biomass. The correlation between gains in oil concentration and leaf biomass was weak and not significant (r = 0.15); while the correlation between oil yield and leaf biomass was very strong and highly significant (r = 0.96). These results highlight the importance of carefully incorporating leaf biomass as a selection criterion in cajuput breeding programs aimed at increasing oil yield.

Keywords:

• essential oil
• improved seed
• selection
• seed orchard
• tree improvement

Acknowledgements

We thank Chris Beadle for valuable comments and suggestions on our manuscript, the Ministry of Environment and Forestry of Indonesia, the Educational Fund Management Institution, National Research and Innovation Agency for funding support, and the field team for setting up the trial and collecting data.

Disclosure statement

No potential conflict of interest was reported by the author(s).