Genotype-environment interaction: expression of field and cellar performances of four Nebbiolo clones (Vitis vinifera L.) in different growing locations in north-west Italy

'Nebbiolo' (Vitis vinifera L.) is one of the most renewed wine red cultivars of North-west Italy from which high quality red long-aged VQPRD wines are produced. The genetic variability of 'Nebbiolo' population is well known and it is expressed by 43 clonal selections officially registered in the National Catalogue. 'Nebbiolo' is cultivated in several districts which differ very much in terms of climatic and soil conditions. The final enological result will therefore depend on the compensative/synergistic influence of the two factors: clone and environment. In order to investigate the clone-site interaction, field and cellar performances of four widespread selected clones of 'Nebbiolo' (CVT 71, CVT 142, CVT 185 and CVT 423) were comparatively monitored over two years (2013-2014) in four experimental vineyards located in different districts of Piedmont, where 'Nebbiolo' is mainly cultivated. The four locations differ in terms of cultural and environmental conditions (row exposition and sloping, vine density, soil texture and pH, etc.). Agronomic performances of clones were assessed during the growing seasons, grape composition was evaluated at harvests with particular attention to phenolic compounds. Successively grape small-scale winemaking, wine chemical composition and sensory evaluations were performed for each clone and site to characterize the final quality of wines with particular attention to sensorial aspects. The results confirmed the importance for the grape grower to know not only the attitudinal characteristics of the clones but also their environmental stability to make the right choice when planting a new vineyard.