The Effects of Some Stressors on Primary and Secondary Metabolites in cv. 'Cabernet-Sauvignon' and cv. 'Merlot' (Vitis vinifera L.)

compounds, aid in biotic and abiotic stress responses and offer significant health benefits. Phytoalexins are secondary
metabolites with diverse chemical structures across plant species, including resveratrol. The aim of this study was to
determine the effects of abiotic and biotic stresses applied 5 days before harvest on the primary and secondary metabolites
in grapes, as well as their effects on resveratrol concentration. The main reason for these late-stage applications is to ensure
the healthy survival of the vines after 2 years. The trial is located at 41°01018.9000N and 27°28016.5300E, with an elevation
of 223m above sea level. We selected 13-year-old ‘Cabernet-Sauvignon’/SO4 and ‘Merlot’/SO4 graft combinations. The
stresses applied included shock action, leaf injury, leaf removal, ultraviolet C (UV-C) application, vibration, Botrytis
cinerea Pers ex. Fr. inoculation, and control. It was found that the stress applications did not have an effect on primary
metabolites. However, in terms of secondary metabolites, the lowest values were detected in the control treatment with
total tannins (3.42mg kg–1), total anthocyanins (917.12mg kg–1), total phenolics (2769mg kg–1), resveratrol (4.45mg kg–1),
and total polyphenols (7.56mg kg–1). The highest values were observed in the leaf removal treatment, with a tannin content
of 3.89mg kg–1, total anthocyanin content of 1104.79mg kg–1, and total phenolic content (TPC) of 3422.08mg kg–1.
As a result, it was determined that inoculation with B. cinerea is suitable for increasing resveratrol content in ‘Merlot’.
Additionally, leaf injury, UV-C, and vibration were found to be effective. For ‘Cabernet-Sauvignon’, UV-C application is
recommended. In addition, inoculation with B. cinerea, leaf removal, and leaf injury are also effective.