Inheritance of tree characters in apple

Eight apple varieties were crossed according to the half-diallel mating design. The seedlings of 28 crosses were investigated in the nursery and the orchard. Significant differences were found among crosses for tree height and trunk diameter, crown diameter and density and internode length and diameter. General combining ability (GCA) was highly significant. Specific combining ability (SCA) was significant for all characters in most years. However, the mean squares for GCA were several times greater than mean squares for SCA. It indicates that the investigated characters are under additive gene control and selection of parents on the basis of their own phenotypes will result in rapid genetic gains. The results indicate that it is possible to evaluate combining ability of apple varieties for tree characters in the juvenile period and to use them in breeding for dwarfness and other desirable characters.