LAUSR

Abstract Plums are climacteric fruits with edible fleshy mesocarp. They belong to different species of the genus Prunus (Rosaceae) and consist of many autochthonous genotypes characterized by particular organoleptic characteristics and nutraceutical potential. In this study, chemical properties (i.e., soluble solid content, pH, titratable acidity, total phenolic content and antioxidant activity) of seventeen plum genotypes (four largely diffused varieties plus one clone and thirteen autochthonous genotypes) were investigated during six crop years. A discrimination among the genotypes, with respect to ripening time, pomological and nutraceutical traits, was obtained applying hierarchical cluster analysis (HCA). In addition, a principal component analysis (PCA) was calculated to evaluate the genotypes similarity and stability during the six crop years. Finally, correlation studies among all traits and crop year’s meteorological conditions were also investigated. The results showed significant differences in chemical properties in relation to the genotype, crop years and ripening time highlighting higher titratable acidity, total phenolic content and antioxidant activity in autochthonous genotypes. Contrary, the largely diffused cultivars (or commercial varieties) showed the highest soluble solid content and the lowest acidity values. HCA and PCA allowed to discriminate the autochthonous plum genotypes ‘Regina Claudia’, ‘Prungaccino di Velletri’ and ‘Prugna di Dro’ considering their phenols amount and stability across the six crop years. In many cases, their concentrations resulted higher than those found in the commercial varieties ‘D’Ente 707’, ‘French Prune’ and ‘Stanley’, maintaining good soluble solid content and titratable acidity ratio (SSC/TA). Finally, hierarchical cluster analyses for SSC and TA traits plotted the samples in relation to ripening time. These results could promote specific autochthonous genotypes, to establish a database that could permit to improve the utilization of specific genetic resources in breeding programs.