Enhancing wine grape quality in hot climate viticulture regions: The role of shading net coverage and light transmittance

This study aimed to enhance the economic benefits of shading nets in improving the quality of grapes and wine in warm climate regions. In 2022 and 2023, the effects of different light-selective shading nets (red, white, and black) at two coverage widths (3 m and 1.5 m) on the quality of Cabernet Sauvignon grapes and wine were investigated in Heshuo County, Xinjiang, China. The soluble sugars, organic acids, anthocyanins, and phenolic compounds present in grapes and wine were analyzed by using the high-performance liquid chromatography (HPLC) and other relevant analytical techniques. The findings indicated that shading net treatments led to a reduction in the sugar content of grapes and an increase in their acid content. Among them, the total acid content of 3 m black nets was increased by 5.47% to 15.86%, and the reducing sugar content was decreased by 6.47% to 7.49%. It is noteworthy that the total phenolic content in wines produced from grapes cultivated under the 1.5-meter-wide red net exhibited a substantial increase, reaching 26.09% in 2022 and 44.37% in 2023, respectively, and the anthocyanin content in the grape skins increased by 16.60% and 14.24% in 2022 and 2023 respectively. Principal component analysis indicated that the color of the shading net had a greater impact on grape quality than the shading width (3 m vs. 1.5 m). These findings provide a scientific basis for the rational use of shading nets and facilitate the selection of materials with reduced covering costs. • Wide shade nets reduce the total reducing sugar content of grapes more than narrow ones. • Narrow red nets are more favourable for the accumulation of anthocyanin in grapes. • Red nets enhance the phenolic content of grapes and wines even more. • The light selectivity of the nets is more likely to affect the grapes than the width.