Global genotype by environment trends in growth traits for Eucalyptus dunnii

Eucalyptus dunnii Maiden (Dunn's white gum) is a fast-growing tall tree with a restricted natural distribution in south-east Australia and favorable wood properties for pulp production. In this study, selected and native forest family seedlots of E. dunnii were evaluated in 17 open-pollinated progeny trials located in Australia, Uruguay, China, Argentina, and Spain for diameter at breast height and total height between the ages of 1 and 7 years. The generality of the factor analytic approach was extended to accommodate unbalance in treatment effects and traits, by modelling each dimension of the genotype covariance matrix as a unique combination of location, age, and trait. Genetic correlations between the two growth traits, between trials and between ages were generally high with only five trials exhibiting average trial-trial correlations below 0.7, indicating genotype by environment interactions were low. Estimated individual seedlot repeatability varied from 0.04 to 0.18 for both traits. The results of this study show that selection and deployment across multiple trials within Australia, Uruguay, China, and Argentina is possible from a single breeding program of E. dunnii, however some environments will require further investigation to determine the drivers of the observed GxE.

Automated summary

The study evaluated selected and native forest family seedlots of Eucalyptus dunnii in open-pollinated progeny trials in multiple countries and found high genetic correlations between growth traits, trials and ages. Results suggest that selection and deployment across trials in different countries is feasible, but further investigation is needed to understand genotype by environment interactions.