Bioactive compounds and quality attributes of pomegranate fruit as affected by continuous deficit irrigation

Pomegranate (Punica granatum L.) is a popular fruit crop known for its nutritional and health benefits. However, water scarcity in many regions of the world has necessitated the adoption of specific strategies to conserve water resources. This study aimed to investigate the impact of continuous deficit irrigation (CDI) on the chemical and biochemical traits of two pomegranate cultivars (cv. Sefri and cv. Wonderful) to assess their response to water stress and their potential adaptability to limited water availability. Therefore, during the developmental cycle of the pomegranate, three irrigation treatments were implemented: a control treatment in which irrigation was applied to fully satisfy crop evapotranspiration (100% ETc), and two CDI treatments, 70% ETc (CDI₇₀) and 50% ETc (CDI₅₀). The undertaken measurements encompassed an intricate examination of fruit chemical, color, and biochemical attributes, coupled with the meticulous quantification of juice phenolic compounds through high-performance liquid chromatography (HPLC) analysis. The results indicated that the influence of water stress on the quality attributes of pomegranate juice significantly varied depending on the genotype. In the ‘Sefri’ cultivar fruits, a pronounced negative impact of CDI was discerned, notably affecting total soluble solids and pH. Conversely, in the ‘Wonderful’ cultivar fruits, no discernible distinctions were identified across all chemical traits between the deficit irrigation treatments and the control fruits. Thus, a pronounced reduction in both total phenolic content and antioxidant activity coupled with an augmentation in hydrolysable tannin content was discerned across both cultivars subjected to CDI treatments. Concerning the impact of CDI on the phenolic fraction, the results revealed a significant reduction in the individual phenolic compounds except for epicatechin in both cultivars and caffeic acid in ‘Sefri’ cultivar fruits, where no effect of CDI was observed when compared to the fully irrigated fruits. In conclusion, given the remaining gaps in our understanding of the impact of continuous deficit irrigation on pomegranate tree resilience, this study represents an initial endeavor to explore water management in pomegranate cultivation within Mediterranean semiarid regions.