Bioactive compounds and quality evaluation of ‘Wonderful’ pomegranate fruit and juice as affected by deficit irrigation

BACKGROUND: Persistent water shortage, typical of Mediterranean agricultural systems, has driven production methods towards the use of regulated deficit irrigation (DI) strategies, which may allow important water savings. To evaluate the extent to which pomegranate (cv. ‘Wonderful’) attributes may differ depending on the irrigation application rates, we investigated the effect of four different irrigation regimes (100, 75, 50, and 25% of maximum crop evapotranspiration – ETC) on their morphopomological, physico-chemical properties, and bioactive compounds. RESULTS: The weight and the size of whole fruits, and the number of arils and their weight per fruit, decreased significantly with the restriction of ETC water volumes applied to the crop. Minor differences were observed in soluble solids, pH, color of fruit skins, arils, and juices, although total acidity, maturity index, vitamin C, glucose, and fructose were not affected. However, total phenol content and antioxidant activity in juices were higher in the samples subjected to the DI treatments than in those submitted to full irrigation, showing the highest value at 50% ETC. A similar trend was found for anthocyanins delphinidin-3,5-diglucoside and delphinidin-3-glucoside, reaching the highest concentration at 50% ETC. Among non-anthocyanin compounds, punicalagins and pedunculagin were more concentrated in the 75% ETc samples. CONCLUSION: The results of the present study indicate that the DI strategy throughout all the growing season is likely to have important implication for the pomegranate's physical, chemical, and phytochemical properties. Knowledge of them is useful in view of their processing and nutritional properties.