The genetic control of flowering precocity was examined in 4 base popu
lation trials of Eucalyptus globulus ssp. globulus in Tasmania, which
include nearly 600 open-pollinated families from 46 collection localit
ies. Flowering precocity (measured as the presence/absence of capsules
and or flower buds at age 4) was found to be highly heritable (h(L)(2
) = 0.47 or 0.59; averaged across 3 or 4 trials respectively), and exh
ibit little genotype by environment interaction. Significant differenc
es 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 precocit
y was generally not genetically correlated with growth (average r(g) =
0.04), indicating that selection for this trait alone would have litt
le impact on early growth. In addition precocious flowering was not si
gnificantly correlated with pilodyn penetration (average r(g) = -0.07)
, although the consistent negative genetic correlation across 4 trials
may be indicative of a weak positive genetic relationship with wood d
ensity. The potential of selecting for precocious flowering as a means
of decreasing the generation interval in breeding programs is discuss
ed.