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

Primary metabolites are essential for plant growth and development, whereas secondary metabolites, such as phenolic 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 degrees 01 ' 18.90 '' N and 27 degrees 28 ' 16.53 '' E, with an elevation of 223 m 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 (3.42 mg kg(-1)), total anthocyanins (917.12 mg kg(-1)), total phenolics (2769 mg kg(-1)), resveratrol (4.45 mg kg(-1)), and total polyphenols (7.56 mg kg(-1)). The highest values were observed in the leaf removal treatment, with a tannin content of 3.89 mg kg(-1), total anthocyanin content of 1104.79 mg kg(-1), and total phenolic content (TPC) of 3422.08 mg 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.