The genetic control of flowering precocity in Eucalyptus globulus ssp. globulus

The genetic control of flowering precocity was examined in 4 base population trials of Eucalyptus globulus ssp. globulus in Tasmania, which include nearly 600 open-pollinated families from 46 collection localities. Flowering precocity (measured as the presence/absence of capsules and or flower buds at age 4) was found to be highly heritable (h2 L = 0.47 or 0.59; averaged across 3 or 4 trials respectively), and exhibit little genotype by environment interaction. Significant differences in the propensity for flowering precocity were observed between the 4 trials and also between different collecting localities. Progenies from localities on the Furneaux Group of islands showed significantly earlier flowering than those from other localities. Flowering precocity was generally not genetically correlated with growth (average rg = 0.04), indicating that selection for this trait alone would have little impact on early growth. In addition precocious flowering was not significantly correlated with pilodyn penetration (average rg = ‚Äö-0.07), although the consistent negative genetic correlation across 4 trials may be indicative of a weak positive genetic relationship with wood density. The potential of selecting for precocious flowering as a means of decreasing the generation interval in breeding programs is discussed.