Grapes grown under warm climate conditions tend to show less color development, and this phenomenon is attributed to low anthocyanin accumulation in berry skin in response to high temperature during ripening. 'Benitaka' (Vitis vinifera L.) is a table grape that shows poor color development when grown under a subtropical condition, and the exogenous application of (S)-cis-abscisic acid (S-ABA) is a recently developed technique used to overcome this difficulty. Trials were conducted during two crop seasons in a commercial vineyard containing 11-year-old 'Benitaka' vines grafted onto 'IAC 766 Campinas' rootstocks in Marialva, State of Parana (PR), Brazil. The vines were trained on an overhead trellis system, covered with a black plastic mash, and spaced 3.0 × 6.0 m apart. A randomized block design was used and treatments included the application of 400 mg L −1 of S-ABA at different stages of ripening, as follows: Control (no application); At pre-veraison (PRV) (7 days before veraison); At veraison (V); and At post-veraison (POV) (7 days after V). A second application was performed for all treatments, 10 days after the first application, except for the control. The analysis of berries included, total and daily anthocyanins accumulation, the color index of red grapes (CIRG), daily CIRG development, lightness (L*), chroma (C*), hue angle (h°), mass, length, width, firmness, total soluble solids (TSS), titratable acidy (TA), the index of maturation (TSS/TA), and total polyphenols of berries. The exogenous application of S-ABA from PRV to POV significantly enhanced the contents and rates of total anthocyanins accumulation and the CIRG of 'Benitaka' table grape; however, the application at PRV and V provided a higher response. A stronger correlation exists between anthocyanin concentration and the color index of berry skin, however, the main physicochemical characteristics of berries are not significantly affected by the use of S-ABA. Berry firmness varies in response to S-ABA application, but not to an extent at which it compromises berry quality for commercial use.

In colored table grapes, the anthocyanin contents are inhibited by the high temperature during ripening and berries suffer a lack of skin color, thus affecting their market value. In order to overcome this issue, a research study was planned to evaluate the influence of (S)-cis-abscisic acid (S-ABA) on rates of anthocyanin accumulation in table grapes when applied at different timings of ripening, and to quantify the gradual increase of berry color. The study was conducted in a commercial vineyard of ‘Benitaka’ table grapes (Vitis vinifera L.), grown under double annual cropping system in a subtropical area. The trials were carried out during two consecutive seasons (i.e., summer season of 2015 and off-season of 2016). The treatments used for the experiments contained 400 mg L−1 S-ABA applied at different timings of veraison (the onset of ripening), as follows: control (with no application); at pre-veraison (PRV); at veraison (V); and at post-veraison (POV). For all S-ABA treatments, a second application was performed 10 days after the first application. Berries were analyzed for weekly and daily anthocyanin accumulations, weekly and daily color index development (CIRG), total soluble solids (TSS) content, titratable acidity (TA), and maturation index (TSS/TA). Grapes subjected to exogenous application of S-ABA at any time of veraison, especially at PRV or at V, significantly increased the anthocyanin accumulation as well as berry color index development. Other chemical properties of grapes (i.e., TSS, TA, and TSS/TA evolution) were not affected by the use of S-ABA and followed a predictable pattern in relation to days of berries ripening.

The application of S-ABA enantiomer to clusters of poor pigmentation cultivars can improve grape color. The aim of this study was to assess whether S-ABA applied to clusters of the new hybrid ‘BRS Melodia’ seedless grape can improve its color characteristics and to evaluate the consumer acceptance. The following treatments were evaluated: Control; S-ABA at 200 mg·L−1 7 days after veraison (DAV); S-ABA at 400 mg·L−1 7 DAV; S-ABA at 200 mg·L−1 7 DAV + 200 mg·L−1 21 DAV; and S-ABA at 400 mg·L−1 7 DAV + 400 mg·L−1 21 DAV. To apply the treatments, clusters were sprayed using a backpack sprayer until runoff. The exogenous application of S-ABA significantly improves the color of berries of ‘BRS Melodia’ seedless grape, particularly at a concentration of 400 mg·L−1 in two applications, at 7 DAV and 21 DAV, resulting in clusters with greater consumer acceptance through visual-sensory analysis. Regardless of concentration or application timing, there was no change in the physicochemical characteristics of the berries or clusters, nor in the number of shoots per cane or clusters per shoot in the season after its application.

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