Pomegranate plasticity to water stress: attempt to understand interactions between cultivar, year and stress level

This work investigated the effects of sustained deficit irrigation (SDI) on yield components and fruit physico-biochemical proprieties of two pomegranate cultivars, ‘Sefri’ and ‘Wonderful’ 21 trees each, in Sais plain (northern Morocco) over two consecutive seasons (2018–2019). Irrigation treatments consisted of a control, irrigation applied to fully satisfy crop evapotranspiration (100% ET(C)), and two SDI treatments: 70% ET(C) (SDI(70)) and 50% ET(C) (SDI(50)). The effects of the SDI treatments differed between cultivars and years. During the first year, yield and fruit weight were significantly reduced in ‘Sefri’ under SDI(50). The same effect was also observed in the second year under SDI(70). In ‘Wonderful’, a significant decrease in yield occurred in the second year under both SDI regimes. Fruit juice content was reduced in both cultivars, particularly under SDI(50), with no significant effect on fruit aril content and aril weight. As for juice chemical properties, it was observed a decrease in total soluble solids, especially under SDI(50). Furthermore, a significant decrease in juice soluble sugars content was observed in the first year for both cultivars. Total polyphenols content has significantly diminished in the second year in both cultivars. Likewise, total anthocyanins level displayed the same pattern, particularly in ‘Wonderful’. The findings suggest that SDI decreases yield and fruit quality even under moderate regime of 70% ET(C). These negative effects may be dramatic depending on pomegranate genotypes, as observed in ‘Sefri’, compared to Wonderful variety. The great impact on species behavior toward water stress was particularly driven by the irrigation treatment, of which the interaction with the cultivar factor had the higher impact on the model. As many areas of how sustained deficit irrigation impacts pomegranate tree resilience are still needed to be investigated further, this study is a first attempt to explore water management in pomegranate in the Mediterranean semiarid lands.