Influence of nitrate fertilization on Cd uptake and oxidative stress parameters in alfalfa plants cultivated in presence of Cd

Plant nutrients might affect the activity and bioavailability of heavy metals in the soil –plant environment thus their accumulation in the plant. Little is known about the effect of nitrogen fertilization on cadmium (Cd) uptake by alfalfa “Medicago sativa”. This work aims to characterize the oxidative status, the physiological stress parameters and the Cd uptake in alfalfa « Medicago sativa » exposed to Cd and supplied with nitrogen fertilizers. The experiment was carried out in a green house with alfalfa grown in Cd-polluted soil (3.6 ppm) and amended with two different fertilizers: without NO3 (PK) or with NO3 (NPK) in a sand:peat (v:v) mixture. The following parameters were monitored: Chlorophyll content, Photosynthesis rate, Catalase (CAT) activity, Thiobarbutiric Acid Reactive Species (TBARS) content and Cd bioaccumulation. It was found that NPK fertilization increased mean Cd uptake as well as plant biomass in Cd-exposed plants. Nitrogen supply was also effective in reduction Cd-induces phytotoxicity (Photosynthetic pigments and rate) and oxidative stress alterations. Our results suggest that nitrogen supply may improve the uptake rate of Cd by alfalfa and provide new insights on the importance of nitrogen fertilization towards future phytoremediation applications using alfalfa.