Influence of cluster thinning and girdling on aroma composition in ‘Jumeigui’ table grape

Abstract

Cluster thinning and girdling are common and simple practices applied to improve berry quality in table grape cultivation. However, there is limited information about the accumulation and biosynthesis of the entire aromatic profile under cluster thinning and girdling, notably in table grapes. This research investigated the influences of cluster thinning and girdling (alone or in combination) on aroma profiles, particularly the changes in biosynthesis and accumulation of Muscat-flavored related compounds from véraison to harvest in ‘Jumeigui’ grape. Cluster thinning and girdling (alone or in combination) significantly increased the concentrations of total soluble solids (TSS) and key aromatic compounds at harvest, with higher concentrations of both under cluster thinning than girdling. Berry weight and titratable acidity (TA) were unaffected by cluster thinning, girdling, or in combination at harvest. Linalool, the most abundant and active odorant related to Muscat flavor, accumulated in 28.6% and 20.2% higher concentrations from cluster thinning than control and girdling at maturity, respectively. Furthermore, higher DXS3 transcript abundance in cluster thinning groups might contribute to the increased accumulation of terpenes and linalool in ‘Jumeigui’ grape. The results will contribute to further understand the mechanism of source/sink ratio modulation on aroma accumulation and better apply cluster thinning and girdling for grape production.