Corymbia maculata
Background
In 2004 seedEnergy established a Corymbia maculata trial at Cambridge in south east Tasmania, with the intention of converting the trial to a seed orchard based on the results of a genetic evaluation. In 2005, 2 additional trials were established in northern New South Wales to test the performance of the seed orchard families across a range of planting environments. The Cambridge trial was converted to a seed orchard in 2008.Genetic Material
The Corymbia maculata trials consist of 40 families, purchased from the Australian Tree Seed Centre (CSIRO Forestry and Forest Products), from nine different populations including a first generation seedling orchard. The populations represent a substantial part of the natural distribution of the species, thereby providing a broad genetic background.Seed Orchard Design
and Development
The trials were established as resolvable block designs, with 16 replicates of single tree plots. All trees in the Cambridge trial were assessed for stem diameter, straightness and forking at age 3½ years. Diameter and straightness were found to be under moderate additive genetic control, with heritabilities of 0.52 and 0.48 respectively. Predicted breeding values were combined in an index using assumed economic weights for a saw log breeding objective. The trees were ranked on their index values and the orchard culled to 50% of its original stocking. Elite trees have been identified for seed collection.