Fruit sugar profile and antioxidants of peach and nectarine cultivars on almond×peach hybrid rootstocks

Individual and total sugars in fruit flesh, as well as total phenolics, flavonoids, anthocyanins, vitamin C and antioxidant capacity contents were studied on peach (Prunus persica cv. ‘Tebana’) and nectarine (P. persica cv. ‘Queen Giant’) cultivars budded on five almond × peach hybrid rootstocks (Adafuel, Adarcias, Felinem, Garnem and GF 677) and one P. davidiana × peach hybrid (Cadaman) grown under field conditions. Individual and total sugars were, in general, the highest on Adarcias rootstock in both peach and nectarine cultivars. The highest content of phenolics, flavonoids, anthocyanins, vitamin C and RAC was found on Adarcias, Garnem and GF 677 rootstock for ‘Queen Giant’ cultivar and on Cadaman (phenolics, flavonoids and RAC) and GF 677 (anthocyanins) rootstocks for ‘Tebana’ cultivar. Significant correlations were found among individual sugar contents, as well as between tree vigor and fruit sucrose, glucose and fructose, and between some phytochemical parameters, such as flavonoid and phenolic content. Thus, the less vigorous rootstocks, Adarcias and Cadaman, seem to induce the highest fruit quality, showing higher contents of individual and total sugars. Significant differences were found between cultivars and rootstocks for the different fruit quality traits evaluated. Selecting the right combination of the rootstock and cultivar is important for optimizing chemical characteristics of fruit, especially sugar profile, important quality parameter of peach and nectarine.