Geographic and seasonal variation of biochemical parameters of the European native plum ‘Pozegaca’ (Prunus domestica L.)

Pozegaca’ is the most important native plum genotype in southeast Europe. In this study, the phytochemical fruit composition of the ‘Pozegaca’ ecotype from four different growing regions was evaluated over three growing years. HPLC was used for identification and quantification of sugars, organic acids and phenolic compounds in the fruits. The total effects of growing years and regions on different phytochemical characteristics of ‘Pozegaca’ fruit were analysed using principal component analysis (PCA). Glucose, fructose, sucrose and sorbitol were detected as major sugars in ‘Pozegaca’ fruit. Malic, citric, fumaric and shikimic acids were identified in the studied plum ecotype. Glucose was the predominant sugar and malic acid was the predominant organic acid. A range of phenol compounds was identified, including hydroxycinnamic acids, flavonols, anthocyanins and flavan3-ols. The main factor affecting the fruit quality and phenol composition of the ‘Pozegaca’ plum ecotype in skin and pulp was the growing year. The geographical origin of the ‘Pozegaca’ ecotype appears to have no major influence on the phenol profile of ‘Pozegaca’ fruit. The results showed that air temperature has a strong correlation with sugar compounds (particularly with fructose and sucrose) and with some organic acids (fumaric, shikimic and citric). Related to the accumulation of phenol compounds, air temperature strongly correlated with flavanols (particularly with quercetin 3-rutinoside) and anthocyanins in pulp. Precipitation and altitude were strongly correlated with total phenols in pulp, chlorogenic acid in skin and pulp, neochlorogenic acid in pulp, and all three identified flavanols in pulp. The results showed that specific seasonal and geographic environmental conditions could significantly affect the content of secondary metabolites in ‘Pozegaca’ fruit.