Effects of Se on the growth, tolerance, and antioxidative systems of three alfalfa cultivars.

The aim of this study was to evaluate the selenium (Se) tolerance and exploit the physiological mechanisms in roots, stem, and leaves of three alfalfa cultivars to different concentrations of Se for 60 days. Among three cultivars, Medicago sativa ssp. displayed the highest Se concentrations in tissues, the largest Se amount in aerial parts, the highest bioconcentration factor (BCF) in aerial parts, and translocation factor (TF) under Se stress. Under Se stress, induced O2•- production in roots and leaves and increases in free proline and activities of antioxidative enzymes were observed in M. sativa ssp. Based on the above results, it is concluded that M. sativa ssp. is superior to the other two cultivars for Se phytoremediation, and its well-coordinated physiological changes under Se stress confer the great Se tolerance of this cultivar.