سید مرتضی زاهدی

Drought stress during the ripening phenological period has adverse effects on pomegranate (Punica granatum L.) fruit productivity, characteristics and composition, depending on the drought severity and specific cultivar. This fact underlines the importance of understanding the physiological and biochemical responses of pomegranate under drought stress to improve the quality of fruits. The responses of three commercial Iranian cultivars (‘Malase Saveh’, ‘Mikhosh’ and ‘Rabab-Neyriz’) to slight, moderate or intense drought stress were evaluated, considering yield-related (fruit yield, number of fruits per tree, fruit weight and fruit cracking), metabolite [glucose, fructose, total soluble solids (TSS), titratable acidity, total phenolics (TPC), ellagic acid, total anthocyanins (TAC), abscisic acid (ABA), indole acetic acid (IAA), proline, ascorbic (Asc) and carboxylic acids], and physiological parameters (oxidative stress indexes and activities of key antioxidant enzymes in leaves). Significant decreases in fruit yield (58–68%), number of fruits per tree (39–44%), fruit weight (30–41%), and leaf photosynthetic pigments (23–39%) were observed among cultivars in response to intense drought. On the other hand, significant increases in the levels of ABA, IAA, proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2), as well as the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) antioxidant enzymes were observed in the leaves of all cultivars under intense drought stress. With respect to fruit juice quality, intense drought caused a considerable decrease in the contents of sugars, TAC, TPC, ellagic acid, Asc, TSS, and TA relative to control conditions, while carboxylic acids increased. Slight drought caused small increases in the concentrations of sugars, TPC and ellagic acid in juice. The ‘Malase Saveh’ cultivar showed a better adaptive response to drought stress than the ‘Rabab-e-Neyriz’ and ‘Mikhosh’ ones, sug