RESPONSE AND ACCUMULATION ABILITY OF PERENNIAL RYEGRASS TO PLUMBUM AND CADMIUM STRESS

The object of this study were to evaluate the effect of plumbum and cadmium stress on growth and development of perennial ryegrass and understand the potential of perennial ryegrass for phytoremediation of Pb and Cd contaminated soil, which to provide technical support and application for soil remediation. By the method of artificial potting, Pb were 0, 300, 500, 1000, 1500 mg-kg(-1), Cd were 0, 0.3, 3, 10, 50, 100 mg-kg(-1), Pb-Cd combined were Pb0Cd0, Pb300Cd0.3, Pb500Cd0.3, Pb1000Cd0.3, Pb1500Cd0.3, Pb300Cd10, Pb500Cd10, Pb1000Cd10, Pb1500Cd10. By measuring the seed germination vigor, germination rat, germination index, simplified vigor index, chlorophyll content, photosynthetic, transpiration, photosyntheti-cally active radiation, light use efficiency, water use efficiency. The Pb and Cd content of root, stem, leaf were determined. The results showed that there was no significant difference of the effects of seed germination on low-concentration(300, 500 mg-kg(-1)) Pb2+ stress. There was adverse effects on seed germination for the high-concentration of Pb2+ (1000, 1500 mg-kg(-1)). Low-concentration Cd2+ stress promote seed germination, if the concentration of Cd2+ was more than 10 mg-kg(-1), it showed that inhibition of seed germination. With the increment of Pb2+ concentration, the chlorophyll increased, but Cd showed the opposite tendency. Photosynthetic decreased at first and then increased under Pb and Cd single stress. Photosynthetic reached the maximum value when the concentration of Pb2+ is 1000 mg-kg(-1) or Cd2+ is 10 mg-kg(-1). Enrichment coefficient were decreased with the increase of heavy metal concentration under Pb or Cd single stress. Pb-Cd combined stress has stronger inhibit effect on seed germination than single stress. Accumulation ability of perennial ryegrass were root > stem > leaf. Enrichment coefficient of perennial ryegrass Cd more significant than Pb. Restorative effect of perennial ryegrass for light-polluted soil was better.