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 Japanes e cherry, Prunus spachiana. Eccentric growth of GA(3)-treated branches was observed. In the xylem on the upper side of such branches the pre sence of gelatin fibers, which stained strongly with fast green, was d emonstrated. Moreover, a less dense distribution of vessels and a stee per angle of cellulose microfibrils in the secondary walls of fibers w ere also observed on this side: Similar features were noted in the xyl em 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 upp er side of branches of Prunus spachiana of the weeping type, so that t he branches become to grow upwards, resembling branches of the upright type.