EFFECTS OF PROVENANCE AND GENETIC VARIATION ON THE GROWTH AND STEM FORMATION OF EUCALYPTUS PELLITA IN COLOMBIA

The study reports a genetic analysis of growth and stem formation of Eucalyptus pellita in Orinoquia, eastern Colombia. Families from two restricted locations in New Guinea, collected ex-situ in a local arboretum, significantly outperformed four Queensland, Australia provenances for growth and stem formation. Heritability estimates were low for both traits, 0.05-0.10. Correlation between stem straightness and diameter was positive and strong, but null with height despite height and diameter being strongly related. The mixed model used fitted a spatial component, allowing the estimate of autocorrelations of residuals between neighbouring trees. Autocorrelations changed from slight positive at 1 year old, an indication that the microsite conditions were homogeneous, to moderately negative at age two years onwards, especially for diameter, suggesting competition was starting to impact the performance of neighbouring trees at as early as 2 years old. Despite the reduced size of collection and the possible biases caused by prior ex-situ selection of New Guinea, compared with the native Queensland seed lots, the marked differences found suggested New Guinea sources to be better adapted to local wet and hot conditions.