ALLEVIATION OF CADMIUM-INDUCED CHANGES ON GROWTH, ANTIOXIDATIVE ENZYME ACTIVITIES AND LIPID PEROXIDATION IN CROP SEEDINGS BY MAGNETIC (Fe^sub 3^O^sub 4^) NANOPARTICLES

The widespread accumulation of heavy metals in the environment due to the anthropogenic activities is becoming a problem for the environment. We have evaluated the alleviation of cadmium-induced root growth inhibition and oxidative stress in the seedlings of cucumber and wheat by magnetic nanoparticles (nano-Fe3O4). The results showed that cadmium (Cd) adversely affected the seedling growth of both cucumber and wheat by reducing seed germination and decreasing root and shoot length. Cadmium exposure also significantly decreased the activities of superoxide dismutase (SOD) and peroxidases (POD), and increased the malondialdehyde (MDA) content in the seedlings of both cucumber and wheat. Among the nano- Fe3O4 with different sizes (6nm, 50nm and 100 nm) and bulk-Fe3O4, only the addition of nano-Fe3O4 (6nm) significantly decreased the Cd accumulation, Cd-induced seedling growth inhibition and oxidative stress in the seedlings of both cucumber and wheat. The effect of nano-Fe3O4 (6nm) on oxidative stress was more evident in cucumber seedlings than in the wheat seedlings. The alleviating effect of nano-Fe3O4 to reduce Cd stress in the tested seedlings is probably associated with their adsorption capacity of heavy metals. Our results may imply a size and species-dependent protective effect of magnetic nanoparticles against the toxicity of cadmium during the seedling growth.