INDUCTION OF TENSION WOOD IN GA(3)-TREATED BRANCHES OF THE WEEPING TYPE OF JAPANESE-CHERRY, PRUNUS SPACHIANA

GA(3) prevented the bending of branches in the weeping type of Japanese cherry, Prunus spachiana. Eccentric growth of GA(3)-treated branches was observed. In the xylem on the upper side of such branches the presence of gelatin fibers, which stained strongly with fast green, was demonstrated. Moreover, a less dense distribution of vessels and a steeper angle of cellulose microfibrils in the secondary walls of fibers were also observed on this side: Similar features were noted in the xylem of the branches of cherry trees of the upright type, but they were not found in GA(3)-untreated control branches of trees of the weeping type. These results suggest that GA(3) induces tension wood on the upper side of branches of Prunus spachiana of the weeping type, so that the branches become to grow upwards, resembling branches of the upright type.