Vitis vinifera L. variety Syrah sprayed with ZnSO4: Effect on fruit quality and winemaking

In grapevines, Zn is essential for normal leaf growth, shoot elongation and pollen development, allowing a fully developed berry. In this context, using as a test system Vitis vinifera L. variety Syrah, this study aimed to assess the interactions between Zn enrichment in grapes and sugars and fatty acids profiles, further considering the sensory implications of red wine production. Vineyard conditions of the soil were assessed to ensure the natural optimal development of grapevines and the workflow for Zn enrichment considered three treatments: foliar spray with water (control) and with ZnSO4 (at 450 and 900g.ha-1).  After the 2nd foliar application of ZnSO4, only minor changes of Zn, Ca and P contents were found in grapes (the levels of K, Cu and S increased significantly with ZnSO4 (450 g.ha-1). At harvest, the grapes submitted to foliar application of ZnSO4 showed significantly higher levels of Zn (between 33.38 - 54.41%), but significant deviations in sugars (sucrose, glucose and fructose), fatty acids (C18:0, C18:1, C18:2, C18:3, C16:0, C<16:0) and color parameters were not found. After winemaking, relative to the control, a higher content of Zn persisted (60.59 - 63.82%), without impairing the characteristics desired by consumers. In fact, the wine with ZnSO4 (900 g.ha-1) was the most sensorially accepted.
Keywords: Foliar spraying with ZnSO4; Grapes enrichment with Zn; Nutrient’s interactions; Sugars and fatty acids profiles; Vitis vinifera L. variety Syrah; Winemaking.