Heterosis is a widely occuring biological phenomenon in both the plants
and animal species. The exploitation of heterosis is a common objective
in plant breeding. In forest tree breeding this usually takes the form
of strategies to avoid inbreeding depression or the exploitation of
positive heterosis through deployment of high performing full sibs in
either family or clonal forestry. The tailoring of tree in future
biomass production by genetic manoeuvring holds a great promise.
Depending upon breeding objectives, both positive and negative heterosis
is useful for crop improvement. In general, positive heterosis is
desired for yield and negative heterosis for early maturity. The
manifestation of heterosis has enabled plant and tree breeders to
significantly improve the tree performance by exploiting hybrid vigour.
The many studies on quantitative genetics in forestry over the past 20
years have helped to advance breeding populations. With the availability
of modern molecular tools, scientists can begin to explore the
phenomenon of heterosis into its individual genetic components should
provide new help to guarantor a plentiful supply of quality products for
the future generations.