Abstract: This paper studied the effects of different concentration (0, 10, 30, 50, and 100 μmol·L^-1) CuSO₄on the leaf physiological and biochemical characteristics of Medicago sativa seedlings cultured with 1/4-strength Hoagland nutrient solution. In treatments 30, 50, and 100 μmol·L^-1 of CuSO₄, the leaf H₂O₂, OH·, and MDA contents and Fe-SOD and EST activities increased, and GSH and AsA contents increased significantly. With increasing concentration Cu, the POD, GR, and APX activities increased gradually, and the CAT and G6PDH activities decreased after an initial increase. In treatments >10 μmol·L^-1 of Cu, the capacity of leaf antioxidative system in reactive oxygen species scavenging increased to prevent the injury from copper-induced oxidative stress.

Key words:  Medicago sativa, copper, antioxidative enzyme, esterase