Use of selenium to alleviate naphthalene induced oxidative stress in Trifolium repens L

Polycyclic aromatic hydrocarbons (PAHs) are among the most dangerous of environmental contaminants, due to their toxicity, carcinogenicity and mutagenicity. This study investigated the use of selenium (Se) to protect plants from the toxic effects of naphthalene (NPH). Exposing Trifolium repens L. (white clover) to a high concentration of NPH (soil spiked to 500mgkg^-1) for 60 d significantly decreased biomass, CO₂ assimilation rate (Pn), stomatal conductance (Gs) and intercellular CO₂ concentration (Ci), while inducing production of H₂O₂ and malondialdehyde (MDA). Application of Se (soil spiked to 0.5mgkg^-1) to plants exposed to NPH clearly protected the plants; biomass, Pn, Gs and Ci were significantly higher and contents of MDA and H₂O₂ decreased. The protection provided to Trifolium repens L. by Se is attributed primarily to an increase in photosynthesis and a decrease in oxidative stress. This study demonstrates that a low concentration of Se protects plants against oxidative stress induced by NPH and can provide a means for improving phytoremediation in PAHs contaminated soils.