Abstract:

The genetic effects of general and specific combining ability, male, female, and specific reciprocal cross were analyzed for height, DBH, volume, crown-width, under branch height, crook degree and ratio of branch to shoot in Eucalyptus maidenii. Three quantitative characters, i.e. height, DBH, volume were focus, and their genetic effects were discussed in detail. It was found that the specific reciprocal cross(SRE) was the most important for quantitative characters, then, the male effect(MAL). The general combining ability(GCA) had just less affect height and under branch height, almost zero for the other traits. Specific combining ability(SCA) just affect crook degree and under branch height, but the female effect(FEM) was more important on crown-width, under branch height and ratio of branch to shoot. Two parents were good materials with high value of GCA to the used for establishing next generation seed orchard. Eight combinations were dominant on quantitative characters. It was the best breeding strategy that cross breeding, then superior trees selected from combinations for vegetative propagation, but selection breeding, i.e. establishing seed orchard can not be significantly improved base on the sampling population. Inbreeding depression was very serious in this species.

Key words: Eucalyptus maidenii, Diallel mating, Genetic effects, Combining ability, Growth traits