The Effect of Putrescine and Salicylic Acid on Physiological Characteristics and Antioxidant in Stevia Rebaudiana B. Under Salinity Stress

In order to investigate the effect of putrescin and salicylic acid on some physiological and antioxidant properties of stevia under salinity stress, a factorial experiment was conducted in a completely randomized design with three replications. In this experiment, samples were exposed to different concentrations of putrescine (0, 0.5 and 1 mM), salicylic acid (0 and 0.5 mM) and salinity (0, 75 and 150 mM of NaCl). The results showed that putrescine solubilization at different concentrations caused a significant increase in chlorophyll spray values ​​and antioxidant enzymes of catalase and peroxidase, while the amount of malondialdehyde and relative humidity content were decreased. This research showed that salinity reduced the photosynthetic pigmentation and increased antioxidant enzyme activity. Also, the use of salicylic acid resulted in an increase in the amounts of catalase and peroxidase enzymes. Based on the results of interaction between putrescine and salinity, the photosynthetic pigments and anthocyanin contents were increased by increasing putrescine at different levels of salinity compared to the control sample. Also, the catalase and peroxidase enzymes have significantly increased. With respect to mean interaction effect of putrescine, salicylic acid and salinity, an increase in leakage levels was observed with increasing levels of putrescine levels at 75 mM level of salinity and 0.5 mM level of salicylic acid. In salinity level and salicylic acid concentration of 0.5 mM, the amount of malondialdehyde decreased with decreasing amount of putrescine, and the amount of peroxidase enzyme increased as compared to the control sample that caused resistance of this plant to salinity stress. Therefore, the application of both concentrations of putrescine and salicylic acid would be effective and recommendable.