Genetic parameters and potential gains from breeding for biomass and cineole production in three-year-old Eucalyptus polybractea progeny trials

ABSTRACT Eucalyptus polybractea is a mallee eucalypt with potential use as a perennial biomass crop for dryland agriculture in southern Australia, in addition to its established success as a source of eucalyptus oil. Sixty-six indigenous, open-pollinated families from West Wyalong and surrounds in New South Wales were tested in trials at Newdegate, Western Australia; Drummartin, Victoria; and Condobolin, New South Wales. Growth was fastest at Condobolin, followed by Drummartin then Newdegate. The estimated cross-site genetic correlation was rg = 0.85 ± 0.16 between Newdegate and Condobolin, rg = 1.08 ± 0.35 between Newdegate and Drummartin, and rg = 1.03 ± 0.32 between Condobolin and Drummartin. Estimated gains suggest that genotype × environment interaction was not practically significant. Narrow-sense heritability for biomass production was ĥ2 = 0.18 ± 0.07 at Newdegate, ĥ2 = 0.05 ± 0.04 at Drummartin and ĥ2 = 0.32 ± 0.08 at Condobolin. Heritability of leaf cineole concentration at Newdegate was ĥ2 = 0.38 ± 0.09. The genetic correlation between leaf cineole concentration and biomass production was rg = 0.07 ± 0.19 and the phenotypic correlation was rp = −0.12 ± 0.03. Compared to selection on either tree biomass or leaf cineole concentration, index selection incorporating both whole tree biomass and leaf cineole concentration is most effective when looking to maximise both cineole yield and biomass production.