Application of Jasmonate to alleviate drought Stress in Pomegranate by regulating of antioxidant activities and physiological enzymes

This study aimed to investigate the effects of drought stress (DS) levels, applied using field capacity (FC) (normal irrigation, 70% FC, 40% FC, and 20% FC), and Jasmonic acid (JA) treatments (0, 5, 25, and 50 µM) on the physiological and biochemical traits of pomegranate. The evaluated parameters included relative water content (RWC), SPAD, maximum quantum efficiency of photosystem II (F _V /F _M ), proline, membrane stability index (MSI), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), glutathione reductase (GR), as well as non-enzymatic antioxidants including phenolic compounds and total antioxidant capacity. The results indicated that DS significantly reduced RWC (by up to 49%), SPAD (45%), MSI (47%), and F _V /F _M (59%) under drought 20% FC, while H₂O₂ and MDA levels increased by 55% and 78%, respectively, under the same conditions. However, JA treatments at 25 and 50 µM alleviated the adverse effects of drought stress, with the most pronounced protective effects observed under 40% FC, followed by 70% FC. The 50 µM of JA treatment induced a substantial increase in SOD (114%), CAT (172%), APX (143%), POD (93%), GR (93%), proline (235%), phenolic compounds (141%), and total antioxidant capacity (131%). Furthermore, this treatment mitigated the decline in RWC (23%), SPAD (22%), F _V /F _M (29%), and MSI (22%) under 20% FC. These findings suggest that JA application enhances drought tolerance in pomegranate by activating both enzymatic and non-enzymatic antioxidant defense systems, and preserving MSI, RWC, and photosystem II efficiency.