Biofortification of Se and induction of the antioxidant capacity in lettuce plants

The aim of the present work is to analyse the way in which Se fertilization in both Se forms applied at different rates can affect the production and accumulation of Se and the foliar antioxidant capacity in lettuce plants Lactuca sativa L. cv Philipus. After different rates of sodium selenate and selenite were applied (5, 10, 20, 40, 60, 80, 120 mu mol L-1), the foliar biomass, lipid peroxidation, Se accumulation, antioxidant compounds, and the antioxidant capacity were analysed. Our results indicate that the less toxic form was selenate, as it induced greater biomass, higher Se accumulation, and more antioxidant compounds than did selenite. The treatment of 40 mu mol L-1 proved the most suitable for lettuce plants, as the antioxidant capacity and Se accumulation augmented without diminishing biomass, and making the two these lettuce plants healthier than control plants for human consumption, in comparison to control. Finally, regarding the antioxidant capacity test used (the ferric reducing ability of plasma [FRAP], 2,2-diphenyl-1-picryl-hydrazyl [DPPH] and reducing power), only FRAP showed a significant relationship with the different antioxidant compounds, while ascorbate best reflected the effect of Se on the antioxidant capacity under our experimental conditions. (C) 2008 Elsevier B.V. All rights reserved.