Effect of foliar application of putrescine to enhance drought tolerance of Persian walnut (Juglans regia L.) seedlings

To study the effect of foliar application of putrescine on enhanceing drought tolerance of Persian walnut (Juglans regia L.) seedlings, an experiment had been carried out as factorial based on completely randomized design in a controlled greenhouse with 9 treatments and 20 replications. In this study, treatments were putrescine (0, 0.5 and 1 mM) and three stress levels including control (80% of field capacity), moderate drought stress (50% field capacity) and severe drought stress (20% field capacity). The results of morphological, physiological and biochemical parameters showed that these parameters were affected by the stress levels as well as different concentrations of putrescine. Foliar spray of 1mM putrescine affected the physiological and biochemical parameters and enhanced the tolerance of Persian walnut seedlings to drought stress through improving antioxidant activity systems (via increasing catalase, ascorbate peroxidase and guaiacol peroxidase). The highest rate of shoot length (35.67 cm), leaf area (303.6 cm), leaf relative water content (58.51%), the total fresh weight (47.20 mg) and the lowest ion leakage (28.28%) was related to 1 mM putrescine treatment. It was found that foliar spray of 1mM putrescine was effective on enhanceing drought tolerance of Persian walnut (Juglans regia L.) seedlings.