Influence of partial defoliation on gas exchange parameters and chlorophyll content of field-grown grapevines - Mechanisms and limitations of the compensation capacity

In order to study the compensation mechanisms related to leaf removal, gas exchange response to defoliation as well as chlorophyll content were investigated in field-grown Pinot noir grapevines. Mature 16 years old bearing plants and 2 years old fruitless potted plants were compared. Defoliation treatments were performed 1 week after full bloom. Besides topping, three levels of main leaf removal (3, 6 or all 12 main leaves retained) were combined with two levels of laterals (all retained or all removed). The single leaf measurements (on the 11th main leaf from the base) were carried out from treatment time to fruit maturity.