The main carbohydrate translocated throughout the grapevine is sucrose
Assimilates are translocated from the sites of production (leaves) or storage (organs) to the sinks
ENERGY COSTS OF
TRANSLOCATION
Loading and unloading the sucrose into the phloem: 14% of the amount translocated
The flow in the phloem is passive: no energy required
To maintain the phloem vessels in good shape: energy cost are proportional to the translocation distance
GRAPEVINE GROWTH CYCLE
BUD BREAK TO 4 LEAVES
There is only import from the reserves
5 LEAVES
The first leaf starts exporting carbohydrates
6 - 8 LEAVES
6 - 8 LEAVES
At this stage the new roots start to grow
10 leaves
The shoot becomes almost independent from the reserves
12 - 14 leaves
Bud for the next season start developing
BLOOM
The infloresence in not an important sink for the carbohydrates at this stage
BLOOM
Root growth reaches its maximum peak at bloom
Removing the shoot tip eliminates the competition between the growing vegetative and the infloresence, improving fruit set
FRUIT SET
Lateral shoots with two or more expanded leaves provide carbohydrates to their growing tip and export the surplus to the main shoot, contributing to fruit ripening
Leaves from lateral shoots bearing clusters suply the fruit on the lateral first and export the surplus to the main shoot
VERAISON
At this stage all leaves export to the fruit
RIPENING
AFTER HARVEST
All carbohydrates move downward. There is another flush of root growth
This presenatation was given by Ms Vasconcelos at the 2002 MGGA Annual Meeting and is reprinted here with her permission.
