Genetic improvement for essential oil yield and quality in Melaleuca cajuputi

Melaleuca cajuputi is a multi-purpose tree, best known as an aromatic and medicinal plant for the production of medicinal essential oil that has been commercially used. Among three subspecies cajuputi, cumingiana and platyphylla, M. cajuputi subsp. cajuputi is the main source of cajuput oil industry. Breeding program of M. cajuputi subsp. cajuputi aimed to improve leaf oil yield and 1,8-cineole content has been implemented for the last two decades. In this study, genetic parameters for growth (height and diameter), leaf oil concentration and 1,8-cineole content in the full-sib family progeny trial including 39 families planted in Playen, Gunungkidul, Yogyakarta, Indonesia were examined. Narrow-sense heritability were low for growth traits (h(i)(2) = 0.10 - 0.13) but high for leaf essential oil concentration (0.50) and moderate for 1,8-cineole content (0.21). There were no genetic correlations among growth, oil concentration and 1,8-cineole content. Index selection was used to improve simultaneously both oil concentration and 1,8-cineole content in the M. cajuputi subsp. cajuputi breeding program. The genetic gains for oil concentration increased from -1.19 to 29.67% while the gains for 1,8-cineole content decreased from 6.19 to 0.07%. The scenario that improved 1,8-cineole content by 2.18% was the most optimal selection as genetic responses of leaf oil concentration reached 27.36%.