Variation in growth and Quambalaria tolerance of clones of Corymbia citriodora subsp. variegata planted on four contrasting sites in north-eastern NSW

Abstract

Summary Genetic parameters, including heritabilities, trait-trait correlations and across-site correlations for growth traits and quambalaria shoot blight damage were estimated in four Corymbia citriodora subsp. variegata clonal trials in northern New South Wales, Australia. Additive and non-additive variances were calculated separately to allow the estimation of broad—and narrow-sense heritabilities. Quambalaria shoot blight damage at ages 1 and 3.5 y was under predominantly non-additive genetic control (H2 = 0.02–0.46, h2 = 0–0.17). Growth traits at age 5 y were under moderate genetic control (H2 = 0.32–0.54, h2 = 0–0.54). Growth traits were strongly correlated with quambalaria shoot blight damage. Across-site correlations were low for quambalaria shoot blight damage (rg = 0.13–1.00) but high (>0.8) for the growth traits. Index selection was used to determine the most efficient selection strategies for improvement of growth and disease tolerance.