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Vineyard Management to Optimize Grape Quality in Virus-Free Clones of Vitis vinifera L

Mannini, Franco, Rolle, Luca, Guidoni, Silvia
Acta horticulturae 2003 no.603 pp. 121-126
Vitis vinifera, adverse effects, anthocyanins, canopy, climate, clones, grapes, soluble solids, spatial distribution, vigor, vines, vineyards, virus-free plants, viruses, wines
Severe and costly sanitary protocols are set worldwide in order to propagate only clones free from harmful viruses. Although the overall best performances of virus-free plants are confirmed, some concerns still remained about the occurrence in cool climate areas of negative side-effects on grape quality due to the increase of vegetative vigor and/or of yield often associated to healthy vines. To cope with these occurrences it is necessary to adjust vineyard cultural practices to the changed aptitudes of plants. One experiment was carried out to assess the effect of bunch thinning on heat-treated or virus-infected (GLRaV-1+GVA) plants of the same clone of 'Grignolino'. The healthy vines showed to be much more responsive to the treatment allowing wider margin of quality improvement as also confirmed by wine sensory tastings. A second trial was carried out confronting three different vine spacing, i.e. vine densities, to cope with the strong increase of vigor in 'Nebbiolo Michet' selected clones due to GFLV elimination. The best results were obtained widening the vine spacing. In this case virus-free vines resulted more fertile without increasing bunch dimensions, richer in soluble solids and in berry skin anthocyanins. The better light interception, as shown by canopy density measurements, is the probable explanation of the results.