Effects of gibberellic acid (GA3) application before anthesis on rachis elongation and berry quality and aroma and flavour compounds in Vitis vinifera L. ‘Cabernet Franc’ and ‘Cabernet Sauvignon’ grapes

Abstract BACKGROUND Gibberellic acid (GA 3 ), a plant‐growth regulator, is often used to obtain enlarged table grape berries and induce seedlessness in them. However, the effects of GA 3 on rachis elongation and bunch compactness have seldom been reported in wine‐grape production. We assessed the effects of GA 3 spraying on wine‐grape inflorescences and bunches and their practical implications for viticulture in the Jiaodong Peninsula, China. RESULTS Various GA 3 concentrations were sprayed on field‐grown Vitis vinifera L. ‘Cabernet Franc’ (CF) and ‘Cabernet Sauvignon’ (CS) grapevines before anthesis in the Jiaodong Peninsula, China, in 2015 and 2016. Inflorescence length during berry development was measured, and flavonoids and aroma compounds in the fruit were detected by high‐performance liquid chromatography – mass spectrometry (HPLC‐MS) and gas chromatography – mass spectrometry (GC‐MS), respectively. For both cultivars, 50 and 100 mg L −1 GA 3 caused significant elongation of the rachis, whereas there was no significant effect on inflorescence growth and berry seed number. Anthocyanin, flavonol, and flavan‐3‐ol levels in mature berries were not significantly influenced by GA 3 spraying, whereas C 13 ‐norisoprenoids were modified. CONCLUSION The application of 50‐100 mg L −1 GA 3 prior to grapevine anthesis caused elongation of inflorescences and bunches, and eased cluster compactness in CF and CS, and no negative effects were observed on the yield and seed numbers. The concentration and composition of flavonoids and most aroma compounds were not influenced, except that the norisoprenoids were increased by 50 mg L −1 GA 3 applications. © 2020 Society of Chemical Industry