Effect of Selenium on Growth, Physiological and Biochemical Indices of Garlic Plant (Allium sativum) under Cadmium Toxicity

Increasing the tolerance of plants to biotic and abioticts stresses is a important and debatable subject. Selenium can play a role in mitigating the effects of stress. For this purpose, a factorial experiment was conducted in a completely randomized design with two treatments, cadmium chloride including two levels (0 and 10 mg /kg) in soil and sodium selenate involved three levels (0, 500 and 1000 mg /L) as foliar application with four replication at Shahid Bahonar University of Kerman Research Greenhouse in 2012. The results indicated that cadmium decreased plant biomass, photosynthetic pigments, relative wet content of leaves and increased hydrogen peroxide, but selenium 500 mg /L caused increasing fresh and dry shoot, root and garlic, chlorophyll, carotenoids, relative wet content and decreasing hydrogen peroxide Respectively. Selenium 500 mg /L under cadmium stress decreased malondialdehyde (15.3%) and ion leakage (14%) and increased shoots length (16.1%), root length (19%), proline (11%), reduced sugars (25%), superoxide dismutase (22.2%), catalase (41.8%), ascorbate peroxidase (27%), guaiacol peroxidase (10.1%), polyphenol oxidase (17 %) and non-enzymatic antioxidants anthocyanin (28%) and flavonoid 330 nm (21%) in plant leaves, compared to cadmium treatment. In most cases, selenium 1000 mg /L had a inhibitory effect. According to the results, selenium 500 mg /L can play a role in reducing the destructive effects of cadmium and activating defense system of the garlic plant under cadmium toxicity.