Effect Of Regulated Deficit Irrigation On Anthocyanins And Condensed Tannins In(Vitis Vinifera L.)‘Cabernet Sauvignon' Berries And Wines

The arid and semi-arid areas in the northwest are important wine producing regions in China,but the water resources in this area are scarce and the water use efficiency is low.As an efficient water-saving irrigation mean,regulated deficit irrigation(RDI)can effectively save irrigation water for vineyards and alter the quality of grape berry.In order to further clarify the effects of RDI on important phenolic substances anthocyanins and condensed tannins of grape berry and wine in arid and semi-arid regions,this assay studied the characteristics of anthocyanins and condensed tannins in grape and wine under different RDI levels,also explored the intrinsic correlation between the wine perceived astringency and the condensed tannins characteristics.The study aim to improve the quality of flavonoids in grape berry and wine by using regulated deficit irrigation technology,and provide a reference for the precise management of wine grape and the production of high quality wines.This research adopted Cabernet Sauvignon(Vitis vinifera L.)as the experimental materials in the east of Helan Mountain,Ningxia,carrying out in both 2016 and 2017.Four groups of different irrigation amounts were carried out with 60%(RDI-1),70%(RDI-2),80%(RDI-3)and 100%(CK)of the crop evaporation(ETc),respectively;one was setted as control group treated with of conventional irrigation.The influences of RDI on physicochemical,phenolic compounds,anthocyanins composition and condensed tannin charateristics in ‘Cabernet Sauvignon' grape berry and wine,and the wine astringency were investigated respectively.The main results are as follows:(1)RDI treatment had no significant effect on the transverse diameter,berry volume,berry mass,TSS and sugar content of Cabernet Sauvignon grapes,but decreased the content of titratable acid and increased the ratio of sugar to acid;RDI treatment had no significant effect on the pH,dry extract content and color of Cabernet Sauvignon wine.(2)RDI treatment can significantly increase the content of phenolic compounds in grape skin,especially RDI-1 treatment significantly increased the content of anthocyanins,and the proportion of acylated anthocyanins.(3)RDI treatment significantly altered the content and composition of condensed tannin in the skins,seeds and wines of Cabernet Sauvignon,respectively.The content of condensed tannin calculated on the basis of each berry was significantly affected by RDI treatment.The effect of RDI treatment on condensed tannin content was not significant when calculated on the basis of skin.The RDI treatment significantly increased the condensed tannin MM-GPC in 2017.(4)RDI treatment can improve the wine quality;the correlation between grape skin CT and wine astringency is stronger than that of seeds;wine astringency was positively correlated with CT content,MM-Phl,mDP,ECG-e,ECG-t and extended subunits in 2016 wine,respectively;but the correlation was not significant in 2017.(5)The overall quality of Cabernet Sauvignon grapes and wines is best under RDI-1 treatment.