Tree Breeding in Support of Vegetative Propagation of<i>Eucalyptus grandis</i>(Hill) Maiden
Annotatsiya
SYNOPSIS Eucalyptus grandis is the most important species supplying timber to the market in South Africa. However, serious timber defects, especially high growth stresses resulting in log end-splitting, reduce the percentage recovery in converting logs to solid wood products. Breeding trials have indicated that substantial genetic improvement is possible in growth rate, stem straightness, splitting of logs, penetration of preservatives and even in rootability of cuttings. Moreover, recent success in clonal forestry brought renewed enthusiasm for obtaining large gains through vegetative propagation. However, while gains from vegetative propagation may far exceed gains from sexual breeding the former is “one-off” in nature. Unless new genotypes with superior characteristics are created the gains obtained from clonal forestry will become stagnant. This paper emphasises the need for the maintenance of genetic diversity and continued breeding. It shows that genetic information from family trials will aid in efficiently selecting superior parents to be used for creating new superior genotypes that will eventually be used for growing rooted cuttings.