The interaction effect of salinity stress and superabsorbent polymer on antioxidant enzyme activities of basil

The aim of this study is to evaluate the interaction effect of salinity stress and superabsorbent polymers on physiological traits of basil. A pot experiment was conducted as factorial based on a completely randomized design with four levels of salinity (0, 40, 80 and 120 mM NaCl in irrigation water) and four levels of superabsorbent polymers included (control, Ackoasorb, Stockosorb and Terracottem). The measured traits were soluble protein, antioxidant enzyme activities, malondialdehyde content and essential oil production. Antioxidant enzyme activities of catalase, guaiacol peroxidase, ascorbate peroxidase and polyphenol oxidase at first harvesting and high salinity (120 mM) under Ackoasorb, Terracottem, Terracottem and Ackoasorb usage decreased 52.68, 73.1, 68.07 and 75.35%, respectively, and also at second harvest at highest salinity level (80 mM) the activity of these enzymes under Ackoasorb, Terracottem, Ackoasorb, Terracottem and Terracottem decreased 37.6, 62.5, 46.38 43.06 and 38.47%, respectively.  With increasing salinity the essential oil production decreased and Tracheotem superabsorbent increase it. At first harvesting, a significant positive correlation was observed between malondialdehyde with guaiacol peroxidase (r = 0.751) and at second harvesting ascorbate peroxidase with protein (r = - 0.753) had a significant negative correlations, moreover, significant positive correlations were found between superoxide dismutase with guaiacol peroxidase (r = 0.848), malondialdehyde with guaiacol peroxidase (r = 0.789) and malondialdehyde with ascorbate peroxidase (r = 0.743). The results showed that application of superabsorbents under salinity stress conditions could decrease the severity of this stress and thereby cause to decrease the antioxidant enzyme activities and malondialdehyde amount significantly, but increased the soluble protein and essential oil content.