Impact of thermal conditions on pomegranate (Punica granatum L.) biochemical traits: a comparative study of genotypic responses under contrasting climates

The purpose of this research was to evaluate the effect of thermal conditions on pomegranate (Punica granatum L.) yield, and fruits’ physical and biochemical traits. The impact of thermal conditions was assessed by studying the variations in these properties across three different pomegranate genotypes grown under two contrasting climates. The first is the ‘Ain Taoujdate’ station with a warm climate (control) and the second is the ‘Anouceur’ station with low-temperature conditions. The obtained data showed that the low-temperature stress has a statistically significant effect on yield components and juice quality attributes. The variation of the analyzed parameters varied depending on the cultivars tested with divergent amplitude variations in each experimental year. In the first year of the experiment, a significant reduction of the pomegranate yield was detected, with a respective average of 35% (‘Wonderful’), 37% (‘Sefri’) and 57% (‘Marsi’). The effect of low-temperature conditions on the chemical traits was reported by a reduction in soluble solids content, pH and titratable acidity in the ‘Wonderful’ cultivar. In contrast, this effect was statistically not significant for the ‘Sefri’ cultivar. Biochemically, the effect of the temperature decrease in the pomegranate orchard was reported by a significant decrease in the juice phenolic compounds, anthocyanins content and antioxidant activity in the three cultivars tested. For the soluble sugar content, the effect of thermal stress was statistically not significant in the first year of the experiment in the Moroccan cultivars (‘Mersi’ and ‘Sefri’). The principal component analysis highlighted the most discriminating variations induced by low-temperature conditions, focusing on total soluble solids, pH, phenolic compounds and antioxidant activity. In conclusion, our research suggests that the American pomegranate variety (‘Wonderful’) exhibited greater tolerance to low-temperature conditions than the Moroccan cultivars. These findings have implications for pomegranate cultivation and may provide valuable insights for growers and researchers in optimizing fruit production under varying thermal conditions.