The effect of leaf area to yield ratio on secondary metabolites in grapes and wines of Vitis vinifera L. cv. Sauvignon Blanc

Aim: To investigate the effect of reducing leaf area by shoot hedging in combination with bunch thinning on metabolite concentration and sensorial quality of Sauvignon blanc grapes and wines.Methods and results: Four vine treatments were conducted: shoot hedging/bunch thinning (SH/BT), shoot hedging/no bunch thinning (SH/NBT), full canopy/bunch thinning (FC/BT) and full canopy/no bunch thinning (FC/NBT). Shoot hedging delayed total soluble solids accumulation at the beginning of the grape maturation in SH/BT and SH/NBT treatments. At harvest there were no significant differences in the concentration of hydroxycinnamoyl tartaric acids, glutathione, total soluble solids, titratable acidity and pH value in grape juice between all treatments and methoxypyrazines were below the limit of detection. Lutein concentration in grape berry was higher in treatments without bunch thinning, while there was no significant difference in the concentration of β-carotene and neoxanthin. The highest leaf area to yield ratio (FC/BT) resulted in higher concentration of glutathione in must and higher concentration of thiols in Sauvignon blanc wines. Upon sensory evaluation, the FC/BT wine was best scored for overall quality and heavier tropical aroma, whereas the FC/NBT wine was best scored for fresh tropical aroma and second best for overall quality.Conclusion: Leaf area to yield ratio impacted berry ripening kinetics, grape and wine metabolite composition, and sensorial properties of Sauvignon blanc wine.Significance and impact of the study: The study showed that the highest leaf area to yield ratio resulted in the best overall sensorial quality of wine.