Breeding Strategy for E.Robusta in Southern Florida

Eucalyptus robusta Sm. has undergone two cycles of improvement in southern Florida. In the first cycle, mass selection produced the following realized gains at 4.5 years: height 20%; diameter 6%; and volume 17%. In the second cycle, family plus within family selection produced the following realized gains at 2.6 years: height 40%; diameter 37%; and volume 91%. Combined gains for both cycles indicated the following improvements: cold hardiness 19%; height 27%; diameter 33%; volume 63%; branch size and angle 14%; and stem straightness 9%. Introductions from natural stands in Australia proved to be vastly superior, especially in cold hardiness, to material obtained from naturalized stands in Florida. Future gene pool enrichment efforts in the E. robusta program will place emphasis on Australian collections. Sib analysis estimates of heritability were higher than realized heritability values for the traits assessed in the second and third generation based populations. Generally poor agreement between sib analysis estimates and realized heritability values suggests caution must be exercised in using these estimates of heritability in genetic gain prediction formulas for E. robusta in southern Florida.

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Author(s): William S. Dvorak, E. Carlyle Franklin, George F. Meskimen

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1981

Section: Section 2: Realized Results of Tree Breeding