Biochemical changes in sunflower plant exposed to silver nanoparticles / silver ions

When soil is contaminated with silver (Ag), plants take up Ag and is concentrated in roots and leaves, with its effects reflected in crop health and yield. This study investigated the toxicity of silver nanoparticles (AgNPs) and silver nitrate (AgNO3 as Ag+) to sunflower seeds grown in soils amended with 150 mg/kg of Ag either as AgNPs or AgNO3. Exposure of the sunflower seeds to soils amended with Ag increased plant lipid peroxidation, activities of antioxidants enzymes (catalase, superoxide dismutase, glutathione-S-transferase), peroxidases (glutathione peroxidase pyrogallol peroxidase, guaiacol peroxidase), oxidases (ascorbate oxidase), urease, total phenolic compounds, vitamins (retinols, alpha-tocopherol and L-ascorbic acid) but inhibited chlorophyll, total carotenoids, total soluble carbohydrates, phenolic compounds and total soluble proteins. In general, AgNO3 increased the above-mentioned parameters in sunflower more than did AgNPs, except for the tested vitamins, which were more affected by AgNPs. The results showed that Ag accumulation in the root > leaf > stem and human food security risk is enhanced in sunflower seeds exposed to Ag compounds.