The effects of Se phytotoxicity on the antioxidant systems of leaf tissues in barley (Hordeum vulgare L.) seedlings

A hydroponic experiment was carried out in a growth chamber to investigate the impact of Selenium (Se) levels on physiological and biochemical characteristics of a barley cultivar. Membrane lipid peroxidation (LPO), proline accumulation and antioxidant activities of some enzymes of barley seedlings under Se toxicity were investigated. Significant increase in thiobarbituric acid reactive substance (TBARS) content, and a stimulation of catalase (CAT, 1.11.1.6), ascorbate peroxidase (APX, 1.11.1.11), glutathione reductase (GR, 1.6.4.2), and glutathione S-transferase (GST, 2.5.1.18) activities were recorded in barley seedlings subjected to 2, 4, 8, 16 ppm Se. Superoxide dismutase (SOD, EC 1.15.1.1) activity was not altered significantly. Plant height and chlorophyll content of the seedlings were also affected significantly in a dose dependent manner by Se treatment. Considerable amount of proline accumulation was also observed in response to Se treatment. The results indicated that increases in the activities of the antioxidant enzymes were not sufficient to protect cell membrane against Se toxicity.