An Investigation to the Vermicompost Efficacy on the Activity Level of Antioxidant Enzymes and Photosynthetic Pigments of Borage (Borago officinalis L.) under Salinity Stress Conditions

Salinity stress is one of the most important factors that limit the growth and yield of agricultural crops in arid and semi-arid regions. Activation of the antioxidant system in plants acts as a defense mechanism to build tolerance against salinity. The present factorial experiment was carried out in a completely randomized design. with four replications to evaluate the effect of salinity and application of vermicompost on the activity level of antioxidant enzymes and photosynthetic pigments borage (Borage officinalis L.) under salinity stress conditions. The study treatments consist of four vermicompost levels (0, 5, 10 and 15 wt % potted soil in dry weight) and four salinity levels (0 (control), 4, 8 and 12 ds/m sodium chloride (NaCl)). The results of analysis of variance (ANOVA) showed the considerable influence of salinity stress and vermicompost on the activity level of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), catalase (CAT) and total chlorophyll enzymes. The findings indicated that incremental salinity increased the activity level of antioxidant enzymes and decreased photosynthetic pigments. The results showed that the use of vermicompost fertilizer raised the levels of chlorophyll a, chlorophyll b and carotenoids significantly compared to the control. Based on the comparison of means of the interactions between salinity stress and vermicompost the maximum activity of antioxidant enzymes was obtained by 15 wt % vermicompost treatment at the salinity level of 12 ds/m NaCl. Therefore, the use of vermicompost as an organic fertilizer, in addition to increasing the activity of antioxidant enzymes and photosynthetic pigments, can be a good way to reduce the negative effects of high levels of sodium and chlorine in soils on the growth of borage.