S17 - Session O4 - Influence of the rootstock and of the environment on phenolic composition in blood orange.

Authors: Giulia Modica *, Laura Siracusa, Giuseppe Ruberto, Mario Di Guardo, Stefano La Malfa, Alessandra Gentile, Alberto Continella

Citrus fruits, and particularly blood orange, are rich in phenolic compounds that affect peel and juice color, sensory, and nutraceutical properties, providing relevant health benefits. Polyphenol content in blood orange is remarkably influenced by genetic and environmental factors such as climate, soil, and agronomic practices, including rootstock adopted. In this context, the aim of the research was to study i) the influence of ten different rootstocks and ii) the effect of winter minimum temperatures on polyphenol accumulation in fruits of blood orange cv. Tarocco Scire. The rootstocks under study were Bitters, Carpenter and Furr citrandarins (hybrids of Sunki mandarin × Swingle trifoliate orange released by the University of California Riverside in 2009), F6P12® and F6P13 (hybrids of Citrus latipes and Poncirus trifoliata released by CREA-OFA in 2014), Troyer, Carrizo and C35 citranges, Swingle citrumelo, and Severinia [ Severinia buxifolia (Poir.) Ten.]. The analyses allowed the identification and quantification of 24 phenolic compounds (6 anthocyanins, 5 flavanones, 1 flavone and 12 hydroxycinnamic acids). The research was conducted for two consecutive years, results highlighted a higher concentration of polyphenols, especially anthocyanins in all the rootstock during the year characterized by particularly low temperatures during fruit ripening. The results showed a significant difference both for each subclass and individual phenolic compound and highlighted a significant effect of both rootstock and environment (and their interaction) on the metabolic profile of the juice.