Effects of different applications of regulated deficit irrigation and bud load on sugars, organic acids, phenolic contents and antioxidant activities of some table grape berries

In this study, two different levels of regulated deficit irrigation (RDI-I and RDI-II) applied vines ,in different phenological period, compared with non-irrigated vines. In addition to irrigation applications, bud load subjects as standard bud load (K) and two times of standard bud load (2K) were examined. In irrigation applications, the highest amount of total colourless phenol content was found in non-irrigation application of Razakı cultivar (372.90 mg/kg) and in bud load applications, highest amount was found two times of standard bud load (K) application of the same cultivar (311.76 mg/kg). In terms of total anthocyanin compound, non-irrigation application of Alphonse Lavallee variety had the highest concentration (272.33 mg/kg). The highest antioxidant activity was evaluated in RDI-II application of Italia cultivar (314.31 mM Trolox/kg); with regard to bud load applications, the highest value was in 2K application of the same cultivar (312.32 mM Trolox/kg) determined by DPPH method. The highest organic acid content was defined in RDI-I application of irrigation of Muscat of Hamburg (7.87 g/kg), and on account of bud load application, the highest concentration was found K application of Italia (7.75 g/kg) based on all varieties. With regard to total sugar concentration RDI-II application of Italia variety had the highest value (215.93 g/kg) between irrigation regimes, and standard bud load application of same variety had the highest value (208.33 g/kg). Generally, our results was found to be in agreement with the given values in literature. In experimental conditions, regulated deficit irrigation and two times of standard bud load (2K) applications can applicate without causing significant decrease on observed characteristics betweeen veraison and maturity stage. Key Words: Grape, irrigation, phenolics, antioxidant activity, sugars