Effect Of Cu～(2+) And Pb～(2+) Stress On Growth And Forage Quality Of Italian Ryegrass

With increasing heavy metal pollution and decreasing arable farmland, more attentions to the utilization of polluted soil have been paid. Forage grasses have wild adaptability and high yielding characteristics, which can grown on the heavy metal polluted soil.Italian ryegrass (Lolium multiftor-um L.) is a famous species used in forage production and turf establishment. In this experiment, Italian ryegrass (cv. Tetragold) was treated by Cu2+ or Pb2+ solutions with different concentrations in tillering period. Response of seed germination, plant growth and nutrition components was studied in pot experiments.The results showed that seed germination was not delayed obviously and that seeds germination rate and seedlings growth were promoted by low Cu2+ and Pb2+ concentration treatment. Compared with the control, with increasing Cu2+ and Pb2+ concentration, seed germination rater length of bud and seed root, dry weight of bud and seed root were decreased rapidly. In addition, the inhibition of Cu2+ treatment to germination rate, bud and seed root growth was stronger than that of Pb2+ treatment. At the same Cu2+ or Pb2+ concentration, the inhibition to root growth was more significantly than to bud growth and seed germination.Growth of young plants was promoted by low Cu2+ or Pb2+ concentrations. With increasing Cu 2+ and Pb2+ concentrations, plant height, tiller number, leaf area per plant, chlorophyll content in leaf and the dry weight of above ground part and root decreased rapidly. Growth was seriously inhibited under high Cu2+ or Pb2+ concentration.Compared with the control, forage quality of Italian ryegrass was not affected heavily under low Cu2+ and Pb2+ concentration. Crude protein (CP) in the stem and leaf increased and neutral detergent fiber (NDF) decreased or affected little. But with increasing Cu2+ or Pb2+ concentration, the NDF content was increased andtotal CP yield of plant was decreased rapidly. Forage quality was dropped significantly.Accumulation of Cu2+ or Pb2+ in root, stem and leaf increased with increasing the treatment concentrations. In the same stress concentration, Cu2+ or Pb2+ content in. root was obviously greater than that of stem and leaf. Cu2+ and Pb2+ were absorbed and attributed in root largely, few were transported to the above ground part.Concerning to the growth, the forage quality and the Cu2+ and Pb2+ accumulation in stem and leaf of Italian ryegrass, it is possible to grow Italian ryegrass for forage production on the soil , which Cu2+and Pb2+ concentration were not higher than 15-30mg/L( or 50mg/kg soil) and 200mg/L (or 500mg/kg soil), respectivelyDuring the experiment, It was also found that Italian ryegrass grew well on the polluted soil, with the concentration of Cu2+ 500 mg/kg (soil) and Pb2+^ 2000m g/kg( soil). So planting and reaping Italian ryegrass on polluted soil is a good method to relive the heavy metal pollution of soil...