Abstract
Tree height and basal diameters of 10 years old Hinoki (Chamaecyparis obtusa) seedling families obtained from 6-clone diallel crosses were measured to study their combining ability. General combining ability was recognized in the growth of their height and basal diameter and there were differences of the general combining ability in reciprocal crossing. Specific combining ability was seen in the growth of their basal diameter. The reasons why the differences of their general combining ability in reciprocal crossing recognized are that there exists a specific clone whose growth is low when they were used as female parents and high as male parents, and that the growth of basal diameter was differentiated by their female parents rather than their male parents. These results imply that not only general combining ability but also differences of their general combining ability in reciprocal crossing and specific combining ability should be taken into consideration when breeding for growth is conducted.
