Aims: The impact of canopy management on the nitrogen (N) content in
grapevines was studied.
Methods and Results: Two trials were carried out between 2001 and 2010
on Vitis vinifera cvs. Chasselas and Pinot noir. The observed factors of
variation were the intensity of lateral shoot removal for the first trial and
the severity of shoot trimming for the second trial. The N content was
evaluated in parallel by leaf diagnosis, the chlorophyll index and the yeast
available N concentration (YAN) found in the musts. When the yields
were the same, a significant dilution of N in proportion to the development
of the leaf area was revealed. Treatments resulting in excessive leaf area
presented N deficiency in the leaves and the musts.
Conclusion: The N content in both the vines and grapes was influenced
by the canopy management (lateral shoot removal and shoot trimming),
and the magnitude of the response appeared to be even greater in the absence
of water stress. In addition, the risk of N deficiency was found to increase
beyond a maximum value of the leaf-fruit ratio.
Significance of the study: Canopy management has a significant influence
on the N content in foliage and grapes, and the risk of N deficiency increases
under a situation that produces an excessive leaf area.
