Articles
REGULATION OF FRUITING IN APPLE ROLE OF THE BOURSE AND CROWNED BRINDLES
The annual growth of these varieties is partitioned essentially onto vegetative sites (coursonnes) that renew and reinforce such growth.
In this case the fruit grower does not intervene significantly at the time of pruning and fruit thinning.
These varietal types show therefore some definite agronomic advantages.
A study of 44 varieties provided evidence of a link between certain morphological characters of the tree and agronomic performance.
We have shown, on unmanaged trees, a relation between the volume of the bourse that terminate the fruiting branch and the biennial bearing.
Acropetal varieties with large bourse rarely alternated, while basipetal varieties, with short spurs ("coursonnes"), tended not to regulate naturally their production from one year to the next.
The bourse appeared to play a major role at the level of the growth distribution on the young fruiting branch (autonomy of lateral shoots), and consequently in the balance between fruiting and vegetative development of each fruiting site.
These studies have led to two research programmes.
The first has involved the setting up of a programme concerning the manipulation of growth partitioning through pruning, in crowned brindles, already in progress for three years in the South of France.
The second concerns the study of transmission of these characters at the level of hybrid families selected for resistance to apple scab.