Uptake and accumulation of copper by roots and shoots of maize (Zea mays L.)

The effects of different concentrations of copper sulfate on root and shoot growth of maize(Zea mays L.) and the uptake and accumulation of Cu2+ by its roots and shoots were investigated in the present study. The concentrations of copper sulfate (CuSO4 x 5H2O) used were in the range of 10(-5)-10(-3) mol/L. Root growth decreased progressively with increasing concentration of Cu2+ in solution. The seedlings exposed to 10(-3) mol/L Cu2+ exhibited substantial growth reduction, yielding only 68% of the root length of the control. The shoot growth of the seedlings grown at 10(-5)-10(-4) mol/L Cu2+ were more or less the same as the control seedlings. The leaves treated with 10(-3) mol/L Cu2+ were obviously inhibited in shoot growth. The fresh and dry weights both in roots and shots decreased progressively with increasing Cu2+ concentration. This fits well with the above mentioned effects of copper sulfate on root growth. Zea mays has considerable ability to remove Cu from solutions and accumulate it. The Cu content in roots of Z. mays increased with increasing solution concentration of Cu2+. The amount of Cu in roots of plants treated with 10(-3), 10(-4) and 10(-5) mol/L Cu2+ were 10, 8 and 1.5 fold, respectively, greater than that of roots of control plant. However, the plants transported and concentrated only a small amount of Cu in their shoots.