Résumé
The effects of bending on shoot growth and lateral development depend on several factors such as the phenological stage, the duration of bending and the angle of re-orientation. An arching experiment was carried out on five apple cultivars to analyze the effects of the phenological stage at which bending was carried out and the position on the shoot on lateral development. Arching was done in the proximal zone of shoots during spring, when shoots were one third of their final lengths and in thedistal zone of shoots after bud organogenesis was completed in the following winter. In all cases, arching was carried out to put shoots under the same mechanical strain. Analyses were done on the arched portion of shoots, with a comparison of the frequencies of laterals in the upper and lower faces of shoots. In both bending treatments, there was a significant increase in the proportion of aborted buds on the lower face, with an increase of sylleptic branches in shoots bent in spring and an increase of inflorescences in shoots bent in winter on the upper face. In shoots bent in winter, inflorescences on the upper face had larger leaves than inflorescences in the lower face. Our results suggested that the effect of branch re-orientation on lateral development may act on both bud organogenesis when bending is carried out during active growth (spring), and bud post-organogenesis when the same manipulation is done during winter before bud break. The interest of branch re-orientation to control branching (intensity and lateral fate) is discussed as an alternative to avoid chemicals