Abstract: 【Objective】The effects of different irrigation amounts on grape berry quality, aroma component accumulation, and the expression level of aroma compounds biosynthetic genes were studied to determine the relationship between irrigation patterns and sensory quality of table grapes and provide a reference for choosing the optimal irrigation amount in root-restricted cultivation. 【Method】The table grape cultivar Shine Muscat was used as the test material, the control group CK, the mild water deficit group DI-1, and the severe water deficit group DI-2 were set up to systematically compare the effect of different irrigation amounts on the morphological indicators, appearance color indicators, aroma components, and expression levels of terpene biosynthetic genes of grape berries. 【Result】Irrigation amount can affect the morphological and texture characteristics of grape berries. Comparing other treatments, the longitudinal diameter of grape berries at harvest time was not significantly affected by irrigation amount, while the horizontal diameter and single berry weight of grape berries in deficit irrigation group were significantly reduced. The firmness of grape pulp also decreased under the influence of deficit irrigation, especially in DI-2 group, of which the pulp firmness was significantly lower than that of other treatment groups. Meanwhile, the glucose content in the grape berries of the deficit irrigation group DI-1 and DI-2 was significantly higher than that in the control treatment, and the fructose content in the severe deficit irrigation group DI-2 was significantly higher than that in other treatments. Mild deficit irrigation of DI-1 exerted little effect on the content of total soluble solids and titratable acid in grape berries. The contents of chlorophyll and carotenoids in grape skins were decreased under the deficit irrigation treatment, but the ratio of the chlorophyll content to carotenoids content in the skins of the DI-2 group was the highest. Additionally, the amount of irrigation also affected the accumulation of aroma components in grape berries. The terpenes compounds, such as limonene, phellandrene, α-pinene, γ-terpinene, (E)-β-ocimene, terpinolene, (E)-furanoxylinalool, linalool, dihydrolinalool, α-terpineol, citronellol, nerol, and geraniol, reached the highest content in the berries of the DI-1 group, followed by the content of terpenes in the DI-2 group, and the lowest in the control group. As for esters, the total content of those compounds in the DI-1 group was the highest, followed by the control group, and the content of the DI-2 group was the lowest. From the total amount of aldehydes, the content in the DI-1 group were significantly lower than those in the control group and DI-2 group. From the total amount of higher alcohols, the content of DI-1 group was the highest, followed by DI-2 group, and the control group was the lowest. There were differences in the expression patterns of terpene biosynthesis-related genes under different irrigation conditions. The expression of VvDXS1, VvDXS2, VvDXR, VvDHR, VvPNLinNer1, VvCSLinNer, VvGwbOci, VvCSbOci and VvGwGer were up-regulated in response to water deficit.【Conclusion】According to the accumulation of aroma components and the comprehensive score of sensory quality, mild water deficit (60%—70% of the maximum water holding capacity in the field) can better promote the formation of aroma quality of Shine Muscat grape berries and improve their commercial value.

Key words: grape, irrigation amount, aroma, gene expression