Morphological and Biochemical Responses of Pomegranate Cultivars to PEG-Induced Drought Stress Under In-Vitro Conditions

Drought stress is one of the major abiotic factors limiting plant growth and agricultural productivity, and its impact is expected to intensify under climate change conditions. Understanding plant physiological and biochemical responses to water deficit is therefore essential for improving drought tolerance in economically important fruit crops such as pomegranate (Punica granatum L.). In this study, the morphological and biochemical responses of three pomegranate cultivars (‘Hicaznar’, ‘Wonderful’, and ‘Acco’) were evaluated under polyethylene glycol (PEG)-induced osmotic stress in in-vitro conditions. Increasing PEG concentrations significantly reduced shoot and root growth in all cultivars, indicating the inhibitory effect of osmotic stress on plant development. In contrast, osmotic stress stimulated the accumulation of stress-related metabolites and antioxidant responses. Total phenolic content increased from 132.4 to 205.3 mg GAE 100 g⁻¹ FW in ‘Hicaznar’, 138.7 to 214.6 mg GAE 100 g⁻¹ FW in ‘Wonderful’, and 129.8 to 198.4 mg GAE 100 g⁻¹ FW in ‘Acco’ with increasing PEG concentrations. Similarly, DPPH radical scavenging activity increased from 34.6% to 58.9%, 36.2% to 61.3%, and 33.9% to 55.7%, respectively. Proline accumulation, lipid peroxidation (MDA), and antioxidant enzyme activities (SOD, CAT, and GR) were also enhanced under PEG-induced stress. These results indicate that PEG-induced osmotic stress triggers significant physiological defense responses and reveals cultivar-dependent differences in drought tolerance in pomegranate.