Selenium Alleviate Cadmium Toxicity by Improving Nutrient Uptake, Antioxidative and Photosynthetic Responses of Garlic

Resumo

Selenium (Se) as a beneficial element in plant growth is able to reduce the adverse effects of abiotic stresses. However, the little attention has been paid to its possible role in cadmium (Cd) detoxification on garlic (Allium sativum L.). Hence, a greenhouse experiment was conducted to study the effect of Se (5 mg/L Na₂SeO₄) in ameliorating the toxic effect of Cd (10^–4, 10^–3 and 10^–2 M CdCl₂) in garlic seedlings. Exposure of plants to Cd stress reduced the biomass and absorption of K, Ca, Mg, Mn, Zn and Cu while that of Na and Fe was increased by raising the Cd concentration in the media. The activities of superoxide dismutase and ascorbate peroxidase enzymes of seedlings treated with Cd at 10^–4 and 10^–3 M concentration increased. However, catalase activity declined linearly with increasing of Cd concentration. The ameliorative effect of Se was more pronounced at 10^–4 and 10^–3 M dosages. Exogenous Se improved photosynthetic rate, transpiration rate and stomatal conductance by 74.00, 64.77 and 58.33%, respectively under 10^–3 M Cd concentration. The beneficial effect of Se could be related to avoidance of cumulative toxicity and increasing of superoxide dismutase and ascorbate peroxidase enzyme exposure to Cd, thus reducing the negative consequences of oxidative stress.