Description et modélisation de la croissance et du développement du pommier (Malus x domestica Borkh.). II. Caractéristiques et distribution spatiale et temporelle des sites de floraison

Abstract

Description and modelisation of growth and development of apple tree (Malus x domestica Borkh . ) . I I . Characteristics and space and temporal distribution of sites of flowering. Young growing apple trees, cvs. Cox's Orange Pippin and Jonagold, have been observed during five years and their flowering sites were recorded. By using a previously established codification, the precise location in space and time of the flowering shoots was made possible. Two phases are described during the development of the tree. During the building of the frame (trunk and two first tiers of branches), a first phase is characterized by a strict alternate bearing regime in the terminal buds of the successive shoots of second and third order. Their eventually marked and prolonged elongation does not hinder their floral initiation, in spite of its late starting. A second phase beginning in third order shoots and later displays repeated flowering on mainly short shoots (""bourse on bourse""), while growth is slackening under joint influence of increase in number of functional apices and fruit load. Both studied varieties behave differently in their way of branching and in its consequences on flowering. Cox's Orange Pippin spreads its branches by numerous sympods upon terminal flowering: two to three bourse shoots sprout from one inflorescence, with an earlier transition to repeated flowering and maintained vigour. On the contrary, Jonagold extends its branches mainly through axillary shoots and, without renewal pruning to sustain vigour, alternate bearing continues until the flowering rate decreases. The exposed method allows thus to characterize varietal behaviors and to predict how to manage them.

Keywords

• Modelisation
• apple tree
• flowering
• alternate bearing