Foliar Spraying with ZnSO 4 or ZnO of Vitis vinifera cv. Syrah Increases the Synthesis of Photoassimilates and Favors Winemaking.

Zinc enrichment of edible food products, through the soil and/or foliar application of fertilizers, is a strategy that can increase the contents of some nutrients, namely Zn. In this context, a workflow for agronomic enrichment with zinc was carried out on irrigated Vitis vinifera cv. Syrah, aiming to evaluate the mobilization of photoassimilates to the winegrapes and the consequences of this for winemaking. During three productive cycles, foliar applications were performed with ZnSO ₄ or ZnO, at concentrations ranging between 150 and 1350 g.ha ^-1 . The normal vegetation index as well as some photosynthetic parameters indicated that the threshold of Zn toxicity was not reached; it is even worth noting that with ZnSO ₄ , a significant increase in several cases was observed in net photosynthesis (P _n ). At harvest, Zn biofortification reached a 1.2 to 2.3-fold increase with ZnSO ₄ and ZnO, respectively (being significant relative to the control, in two consecutive years, with ZnO at a concentration of 1350 g.ha ^-1 ). Total soluble sugars revealed higher values with grapes submitted to ZnSO ₄ and ZnO foliar applications, which can be advantageous for winemaking. It was concluded that foliar spraying was efficient with ZnO and ZnSO ₄ , showing potential benefits for wine quality without evidencing negative impacts.