Effects of cadmium and lead stress on physiological characters of Poa pratensis seedings

A pot experiment was conducted to study the effects of the combined cadmium and lead stress on physiological characters of kentucky bluegrass seedlings. The results showed that the Cd2+ stress had significant (P0.05) effects on the indices including leaf cell membrane permeability, malonaldehyde (MDA) content, chlorophyll content and proline content. leaf cell membrane permeability, MDA and proline content of seedling with 80 mgkg-1 Cd2+ treatment were significantly(P0.05)higher than those of seedling with 40 mgkg-1 Cd2+ treatment whereas the chlorophyll content result was reverse. The Pb2+ stress had significant (P0.05) effects on proline content, leaf cell membrane permeability after 10 d and 20 d treatments and MDA content after 20 d and 30 d treatments. Leaf cell membrane permeability, MDA and proline content of seedling with 1 000 mgkg-1 Pb2+ treatment were significantly(P0.05)higher than those of seedling with 600 mgkg-1 Pb2+ treatment. The significant interaction of Cd2+ and Pb2+ stress was observed in MDA content after 30 d treatment and proline content after 20 d and 30 d treatments. With the extension of heavy metals stress time, chlorophyll content firstly increased and then decreased, leaf cell membrane permeability, MDA and proline content increased gradually.