Estimating the equilibrium position by measuring growth stress in weeping branches of Prunus spachiana Kitamura f. spachiana cv. Plenarosea

The equilibrium position of a current-year branch of the weeping Japanese c herry, Prunus spachiana Kitamura f. spachiana cv. Plenarosea, was estimated by measuring the released strains of growth stresses. In current-year bran ches that were supported with wires to prevent weeping as soon as the branc hes first budded, tensile growth stresses on the upper side were smaller th an those of the control branches. Gelatinous fibers were rarely found on th e upper part of the cross section of the supported branches, whereas the co ntrol branches had many gelatinous fibers on the upper part. The upright or ientation of the supported branches was closer to the equilibrium position than the weeping orientation of the control branches. The equilibrium posit ion of the branches was thought to be in the initial bud direction, above t he horizontal plane, and the weeping style of branch was not the preferred angular orientation for P. spachiana.