|Authors: ||P.E. Lauri, J.M. Lespinasse|
|Keywords: ||Malus domestica (Borkh), fruiting branch, limb renewal pruning, regulation of fruiting|
The Vertical Axis training system was initially developed in 1975 to resolve two main problems with apple orchards:
- excessive tree training time required for the traditional tree forms, and
- an imbalance between the vegetative parts and the fruiting parts of the tree caused by heavy pruning.
From 1975 to 1990, observations on trees trained to the Vertical Axis system led to the conclusion that the fruiting autonomy of the spurs, i.e. the ability of spurs to fruit regularly from one year to the following, could be better achieved on "free growing fruiting branches" than on regularly renewed branches.
The renewal pruning used on Vertical Axis was then abandoned and a modified system, the 'Solaxe' was proposed where all the branches, including the leader, would be bent to suppress the vigorous laterals.
In Solaxe trained trees, training the branch tips in downward position promotes the development of a terminal inflorescence.
It also seems to better balance lateral growth and fruiting on the fruiting branch.
In the Solaxe system the improved balance between vegetative growth and fruiting at the whole tree level appears to be a key factor to obtain fruits of high quality from the top to the bottom of the tree.
Thorough studies of branching and fruiting strategies of fruiting branches belonging to various cultivars have shown that the physiological cessation of growth of a certain proportion of spurs (extinction process) is related to the fruiting autonomy of the remaining spurs.
The improvement of fruiting branch regulation by an early control of the number of fruiting spurs is now investigated on alternating cultivars.
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