TOLERANCE AND ACCUMULATION OF ZINC IN FOUR VARIETIES OF RYEGRASS

A pot experiment with the root rag method was carried out with 4 varieties of ryegrass to investigate the influence of Zn stress(Zn~(2+) at 2,4,8 and 16 mmol/kg soil) on plant growth,antioxidation enzyme activity,proline content,root tolerance index and Zn accumulation.All the varieties showed a high tolerance to Zn stress.Only the higher Zn concentration adopted in the experiment began to inhibit their growth.Shoot proline content declined at first,followed by a sharp increase.POD and SOD activities in the shoot of ryegrass increased with Zn~(2+) concentration,which could be described with a typical parabola.RTI (root tolerance index) of the 4 varieties was 1.Zn~(2+) content in the shoot and the root increased with Zn~(2+) concentration.S/R ratio(Zn content in the shoot/Zn content in the roots) was 1 in treatments with higher Zn(≥ 4 mmol/kg).Of the 4 varieties,Ted produced 57.5% and 150.9% more biomass in the soot and the roots,respectively than the control.Its biomass,RTI,Zn content in the shoot and the roots and Zn transportation were higher than those of the other 3 varieties.