Genetic variation in growth of Eucalyptus grandis grown under irrigation in south-eastern Australia

Summary

Within- and between-provenance variation in growth, to age 4.5 y, of Eucalyptus grandis Hill ex Maiden was investigated in three irrigated provenance-family trials at two localities (Shepparton and Koorlong) in northern Victoria. These trials contained 47 E. grandis seedlots representing both natural stand provenances and planted stands including seed orchards and plus-trees selected in plantations.

Height growth was poor to mediocre, with site averages being 1.4–2.4 m y⁻¹. There was significant provenance variation in some growth traits at each site. Material selected in plantations at Loxton, South Australia, and material from a seed orchard at Coffs Harbour, New South Wales, generally showed the best growth across sites.

At all three sites there were significant differences between families for various growth traits. Estimates of individual-tree heritability for growth traits ranged from very low (0.08) to moderate (0.21). With data combined from all sites, both provenance and family- within-provenance differences proved significant for most traits. In contrast, site by provenance and site by family-within- provenance interactions for growth traits were not significant.

The results are discussed in terms of the importance of provenance selection for E. grandis and the opportunities for genetic improvement in the species through within-provenance selection.

Keywords:

• provenance trials
• genetic variation
• tree breeding
• Eucalyptus grandis
• Victoria