Five-year period of evaluation of leaf mineral concentrations in resistant varieties in Trentino (Northeastern Italy)

Recently new resistant and/or tolerant genotypes to the main cryptogams (downy and powdery mildew) were identified, to be used in enhancing sustainable viticulture. These cultivars (result of interspecific crossings between Vitis vinifera cultivars and other Vitis species of American and Asian origin) are experiencing a relevant expansion in Europe in viticultural regions characterized by high rainfall per year. In two sites of Trentino (Northeastern Italy) with different soil pH levels, and where these conditions are widespread, an important study was scheduled. During the period 2015-2019, fifteen resistant varieties were monitored in order to have information about agronomical and nutritional behavior. Yearly, at fruit set nutritional aspects through leaf analyses and leaf green color (SPAD indexes) were monitored. At pre-veraison, photosynthetically active biomass behavior (Normalized Difference Vegetation Index NDVI indexes) was controlled. Weather conditions of different years strongly changed the availability of nutrients in vines in relation to different genotypes and their color of vegetation and vigor. Collected results allow to suggest interventions aimed at a more suitable nutritional management for resistant varieties, in comparison of Vitis vinifera, above all for nitrogen (N), potassium (K), and zinc (Zn); in particular, for magnesium (Mg), early foliar treatments should be recommended, especially in years where rainfall is concentrated in the spring months