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

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 (r_g = 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.

Keywords:

• breeding
• growth
• diseases
• disease resistance
• genetic parameters
• heritability
• correlation
• interactions
• Corymbia citriodora subsp. variegata
• quambalaria shoot blight
• Quambalaria pitereka