Abstract: Cabernet Sauvignon (Vitis vinifera L.) grape berries were used to investigate the influences of three training systems, single guyot (SG), spur-pruned vertical shoot-positioned (VSP), and four-arm kniffin (4AK) , on non-anthocyanin phenolics, and then the clustering analysis and partial least squares-discriminant analysis (PLS-DA) were conducted to evaluate the characteristic non-anthocyanin phenolic constituents from each training system. The results showed that compared to SG and 4AK, VSP resulted in higher contents of quercetin-3-O-glucuronide, quercetin-3-O-glucoside, kaempferol-3-O-glucoside, quercetin-3-O-rhamnoside in grape skins. Besides, the contents of flavonols including myricetin-3-O-glucoside, isorhametin-3-O-glucoside and syringetin-3-O-glucoside, flavan-3-ols including gallocatechin and catechin as well as protocatechuic acid and vanillic acid in grape skins were higher in SG and VSP than in 4AK, while only procyanin C1 was more abundant in 4AK. The clustering analysis showed that some non-anthocyanin phenolics were significantly affected by vintages, and SG and VSP impacted non-anthocyanin phenolics similarly to each other, but quite differently from 4AK. PLS-DA results showed significant differences in the contents of individual non-anthocyanins among training systems. Flavonols such as quercetin-3-O-glucosid and myricetin-3-O-glucoside were the differential non-anthocyanin phenolic components among training systems, which were found to be more important contributors to VSP and more abundant. In summary, VSP training system plays a positive role in the accumulation of non-anthocyanin phenolics, and can be used in wine grape cultivation in the Guanzhong region of Shaanxi.

Key words: training systems; wine grape; ‘Cabernet Sauvignon’; non-anthocyanin phenolics