The quality of ‘Marselan’ grapes and wines under sunshade nets with different widths and color

Abstract [Objective] Cultivation of winegrapes in hot regions leads to excessive sugar accumulation and severe degradation of organic acids. Through a shading net experiment with the main cultivar of winegrapes in the Helan Mountain East Slope of Ningxia, this study provides a theoretical basis for solving the problem of inconsistent quality of winegrapes in hot regions. [Methods] Using ‘Marselan’ grapevines planted in the field as materials, sugar components, organic acids, and phenolic substances in grapes and wines were determined during the maturation period under white, red, and black shading nets with widths of 0.6 and 1.0 m setting up on both sides of the grapes from the veraison period to the harvest period. [Results] (1) Red sunshade net with 1.0 m width significantly reduced the sugar content of grape fruits, and significantly inhibited the degradation of organic acids in grape fruits and wine. (2) Sunshade net treatment increased the contents of total flavonoids in grape fruits, and reduced the contents of total tannins, total anthocyanins, and total flavantriols in grape fruits. (3) Sunshade net treatment reduced the content of total anthocyanins in wine, and 0.6 m width black sunshade net treatment increased the content of total tannins, total phenols, total flavonoids and total flavantriols in wine. [Conclusion] Shading net width had a better effect on the regulation of sugar and acid content of grape fruits and wine, while shading net color had a better effect on the improvement of non-anthocyanin phenol content of grape fruits and wine. Shading net color and width should be selected according to specific grape production objectives.