Bending shoots stimulates flowering and influences hormone levels in lateral buds of Japanese pear

Flower development of the lateral buds was accelerated in Japanese pear [Py rus pyrifolia (Burm.) Nak.] when vertical shoots were bent at a 45 degrees angle in late June. The indole-3-acetic acid (IAA) concentration in lateral buds on vertical (control) shoots increased in mid-July, while remaining n early constant in bent shoots. The abscisic acid (ABA) concentration of bud s in bent shoots rose between 4 July and 15 Aug., whereas control shoots ex hibited an increase in concentration followed by a decline. Gibberellin(4+7 ) (GA(4+7)) concentration was high on 16 June, and then declined by 4 July, with the decline being greatest in bent shoots. Gibberellin(4+7) concentra tion was higher in the buds on vertical shoots than in those on bent shoots for much of July. The concentrations of zeatin-type cytokinins (CKs) in la teral buds were higher in bent shoots than in vertical shoots. Bending of p ear shoots may weaken competition between buds and other organs through alt ering hormone levels in lateral buds, resulting in acceleration of flower d evelopment.