THE INFLUENCE OF SOME HEAVY METALS ON MEDICAGO SATIVA SEED GERMINATION AND SEEDLING GROWTH

The paper presents the results of a study concerning the influence of high concentrations of lead (Pb), nickel (Ni), and cadmium (Cd) on some physiological, biochemical and morphological indicators in the dynamics of the process of seed germination and in the incipient phases of seedling growth of Medicago sativa. The results underline the specific variations of the analysed indicators (water and dry matter content, total mineral elements content, activities of some oxydoreductase enzymes, content of assimilating pigments, lengths of radicle), determined by the nature of metals and their concentrations used for the treatment of the studied seeds. Regardless of the concentration, Ni, Pb, and Cd determine the intensification of the activity of superoxidedismutase, an indicator enzime of the stress state. Ni, in concentrations of 50ppm and 300ppm, determines the deminishing of the asimilating pigments content, the inhibation of the seeds germination as well as the growth of the length of radicle.