WHAT KIND OF MORPHOLOGICAL TRAITS SHOULD BE SOUGHT IN APPLE SEEDLING PROGENIES IN ORDER TO SELECT REGULAR BEARING CULTIVARS?

The objective of apple breeders at INRA (National Institute for Agricultural Research, France) is to produce cultivars that combine scab resistance and mildew and fire blight tolerance, regular bearing and high fruit quality with a tree structure such as a low tree height that reduces pruning and harvesting costs.
Previously, we have developed a classification system based on tree structure that groups cultivars into four ideotypes.
Recently a twofold study has been conducted to determine the morphological and morphometrical traits of cultivars belonging to the four ideotypes, and the ultimate goal is to determine inheritance of such traits in seedling progenies.
Our results show that, for a given cultivar, the axis slenderness is positively correlated with the internode length, and that both characters seem to be related to a reduced number of growing points through a so-called ‘extinction’ mechanism.
This leads to a high functional autonomy of the remaining laterals, i.e., a high bourse-over-bourse potential.

VI International Symposium on Integrated Canopy, Rootstock, Environmental Physiology in Orchard Systems

P.E. Lauri, J.M. Lespinasse, F. Laurens

Malus x domestica Borkh., apple seedlings, axis slenderness, bourse-over-bourse

https://doi.org/10.17660/ActaHortic.1997.451.87