Zn nutrition of Vitis vinifera White Grapes: Characterization of Antagonistic and Synergistic Interactions by µEDXRF tissue analyses

Nutritional status performs an essential role in agriculture, affecting productivity and keeping crops functioning properly. Despite being required in smaller amounts, micronutrients are also needed for adequate growth, namely Zn (zinc) with regulatory, catalytic and structural functions. Fertilization with Zn is used to ameliorate the deficits of this micronutrient in more susceptible crops such as grapes. Yet, the management of this application must consider the antagonistic and synergistic interactions among nutrients, as it affects their uptake and translocation rates. Therefore, a workflow with three ZnO foliar applications (30% and 60%, 450 and 900 g ha^-1, respectively) in the variety Vitis vinifera cv. Fernão Pires, was implemented in a field located in Palmela, Portugal. The concentration of Zn in the tissues was therefore evaluated by microenergy X-ray dispersion fluorescence (µEDXRF), showing an increase of 1.82 and 2.54 times in the seed and skin of grapes fertilized with a concentration of 60%, compared to control grapes, respectively. Using the same method, a synergistic relationship was observed for macronutrients such as Ca and K, and micronutrients such as Fe, P and Mn. In addition, a complementary analysis of the density of the grapes was carried out to verify changes in quality, with an increase in density with the application of Zn being observed. This study allows us to verify that the concentration of the applied Zn fertilizer brings benefits in the amount of nutrients that are important for development and crops quality.