Influence de la densité de vegetation et de l'effeuillage sur le microclimat, rendement, composition du baie et qualité du vin du cépage portugais Touriga Nacional
The objectives of this experiment were to evaluate the influence of shoot density and basal leaf removal on the
canopy microclimate characteristics and their influence on yield, fruit composition and wine quality of one of the
most important and noble Portuguese red vine varieties – Touriga Nacional.
The experiment was carried out in 2004 on a private enterprise (Dão Sul, Soc. Vitivinícola, SA) of Dão region,
centre of Portugal. The vineyard was grafted in 1991 on 1103 P rootstock. The training system is Royat bilateral
with vertical shoot positioning. Three different shoot densities were applied: D1 – 23 shoots/m row, D2 – 17
shoots/m row and D3 – 11 shoots/m row. At veraison was also introduced another factor: leaf removal (under
clusters).
During the growing season several parameters were measured (leaf area, leaf water potential, leaf gas-exchanges,
leaf layer number, canopy size, intercepted photosynthetically active radiation, fruit composition, yield and
vigour).
Basal leaf removal improved the canopy microclimate by a lower leaf layer number with positive effects on the
interception of radiation at fruit zone, inferior percentage of interior leaves and clusters. On shoot density, it was
verified that the D2 presented the best conditions of canopy microclimate.
Yield was positively influenced by shoot density increase by the augment of the cluster number, while cluster
weight was not affected. Leaf removal had not a significant effect on yield parameters.
The lower shoot density (D3) improved wine quality by greater colour intensity. Leaf removal improved
significantly the wines colour intensity
