Simple rain-shelter cultivation prolongs accumulation period of anthocyanins in wine grape berries.

Simple rain-shelter cultivation is normally applied during the grape growth season in continental monsoon climates aiming to reduce the occurrence of diseases caused by excessive rainfall. However, whether or not this cultivation practice affects the composition and concentration of phenolic compounds in wine grapes remains unclear. The objective of this study was to investigate the effect of rain-shelter cultivation on the accumulation of anthocyanins in wine grapes (Vitis vinifera L. Cabernet Sauvignon) grown in eastern China. The results showed that rain-shelter cultivation, compared with the open-field, extended the period of rapid accumulation of sugar, increased the soluble solid content in the grape berries, and delayed the senescence of the green leaves at harvest. The concentrations of most anthocyanins were significantly enhanced in the rain-shelter cultivated grapes, and their content increases were closely correlated with the accumulation of sugar. However, the compositions of anthocyanins in the berries were not altered. Correspondingly, the expressions of VvF3'H, VvF3'5'H, and VvUFGT were greatly up-regulated and this rising trend appeared to continue until berry maturation. These results suggested that rain-shelter cultivation might help to improve the quality of wine grape berries by prolonging the life of functional leaves and hence increasing the assimilation products.