The effect of seed priming by ascorbic acid on germination traits and activity of some antioxidant enzymes in moldavian balm (Dracocephalum moldavica L.) under salt stress

In order to study the effects of seed priming by ascorbic acid (0, 40, 60 and 80 mM) to increase salt tolerance (0, 100, 150 and 200 mM NaCl) in moldavian balm at germination stage, an experiment was conducted as factorial in a completely randomized design with three replicates at Shahrekord University (2015 year). Evaluated parameters consisted of germination indices (germination percentage and rate, length and dry weight of seedlings and seed vigor index) and the activity of catalase, ascorbate peroxidase and guaiacol peroxidase. Results showed the values of germination indices significantly decreased with increasing salinity degree. However, seed priming by ascorbic acid (40 mM) decreased the negative effects of NaCl on germination of moldavian balm. At this level of priming and under 100 mM NaCl, seed vigor index increased by 32% and at 150 mM NaCl it increased by 2.7 folds. Since the activity of antioxidant enzymes was in coordinate with the effect of optimal concentration of ascorbic acid under salt stress, it is concluded that priming with ascorbic acid decreases oxidative stress due to NaCl by enhancing the activity of antioxidant enzymes in the tissues of moldavian balm and consequently salt tolerance increases in this plant at seed germination.