Biochemical and Antioxidant Responses of Borage Seedlings in Saline Environments

  Background: Although borage ( Borago officinalis L.) is a valuable medicinal plant, no information is available on the responses of this plant to salinity. For this reason, it is necessary to determine responses of this plant to salinity .  Objective: Since germination and early growth stage is one of the most critical phases of plant life under salinity condition this experiment was conducted to determine some responses of borage to salinity at the seedling stage.  Methods: This experiment was laid out in a completely randomized design with three replications and four salinity treatments, including distilled water (EC=0.0dS m-1) and three saline water conditions with EC of 5.0, 10.0 and 15.0 dSm-1.   Results: With increasing EC , the content of free proline, soluble carbohydrates and proteins were increased. Moreover, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO) enzymes were significantly increased. Although seedlings dry weight and emergence percentage were declined with increasing EC, the seedlings had markedly growth/survival under salinity conditions.   Conclusion: The survival and little reduction in emergence under salinity conditions (12.5%) indicated that borage was a salt tolerant species at the early growth stage. This tolerant is certainly due to the enhancement of antioxidant enzymes activities and compatible solutes content. Keywords: Antioxidant enzymes , Borago officinalis L., Osmotic adjustment, Salinity, Seedling stage.