Provenance variation, genetic parameters and potential gains from selection for biomass and cineole production in three-year-old Eucalyptus loxophleba subsp. gratiae progeny trials

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ABSTRACT Ninety families from six provenances of Eucalyptus loxophleba subsp. gratiae were established near Brookton, Western Australia, and Condobolin, New South Wales, and 89 of these same families were established at Monarto, South Australia. All three trials were assessed at age three years for biomass productivity and the trial at Brookton was assessed for leaf cineole concentration. Provenance performance across the sites was most similar between Monarto and Condobolin, while the ranking of provenances was more divergent between those sites and Brookton. Presence or absence of unstable families may change provenance ranking. Additive variance was not significant for the Condobolin trial. Heritability of green biomass at age three years was ĥ2 = 0.19 ± 0.06 and ĥ2 = 0.16 ± 0.05 at Monarto and Brookton, respectively. The heritability of leaf cineole concentration at Brookton was ĥ2 = 0.50 ± 0.08 and whole-tree cineole yield, ĥ2 = 0.11 ± 0.04. The cross-site genetic correlation between Brookton and Monarto was rg = 0.55 ± 0.20, suggesting the presence of some genotype × environment interaction. Removing the six most unstable families resulted in a cross-site genetic correlation of rg = 0.97 ± 0.25. Estimated mean gains from selection scenarios treating Brookton and Monarto as representing two separate environments or as a single environment differed by about 5.0%. The exclusion of six unstable families reduced that difference to 1.4%. Selection on biomass alone may result in a slight increase in total cineole yield per tree but, in this experiment, it resulted in a reduction in mean leaf cineole concentration. Leaf cineole concentration used in conjunction with biomass may be a useful selection criterion in the absence of data for total mass of cineole produced per tree.