Narrow terraces and alternative training systems for steep sloop viticulture – Douro region

In Douro Region, vineyards are usually planted on hillsides with steep sloops. The models currently used for planting those vineyards are, depending on the initial slope of the hillside, vertical planting or terraces. Vertical planting is well adapted when the slope of the hillside is lower than 35-40% and terraces, supported by earthen embankment and one or two rows of vines are the solution for slopes higher than 35 – 40%. Terraces with two planting rows, 3.6 to 4.0m-wide were planted during the 1980s in more than 2500 ha. This solution proved to have disadvantages as to compel the maintenance of the embankment with chemicals for weeds control, high embankment height and consequent problems of instability and erosion.
Due to that in this work it is presented one correct way of constructing narrow terraces 2.5 m wide, using laser systems, and alternatives in control of weeds both in platform and in slope. Because narrow terraces have the disadvantage of a low planting density and yield potential, an experiment was performed with the variety “Touriga Franca”, representative of about 20% of vines in the region, grafted in 110R, two training systems and two planting row distances.
The results of the trial, performed in 2006 and 2007, showed that yield in the double cordon system (LYS 2/3) was respectively 62% and 52% higher than in the traditional vertical shoot positioning (VSP) without negative quality effect on quality of the grapes. Concerning planting row distance, 0.80m achieved a higher yield and better quality than planting at 1.20m.
Narrow terraces, constructed with rigor, proved to be an excellent alternative in planting hillside vineyards, 0.80m a better planting distance than 1.20m, both in terms of yield and on quality and double cordon LYS 2/3 a system suitable to improve yield, without quality detriment, as verified in these two years trials.