Accumulation of Pb and Cd and its effect on Ca distribution in maize seedlings [Zea mays L.]

In the present study the accumulation of Pb and Cd in maize seedlings (Zea mays L., cv. K33 x F2) and its effect on the content of Ca in their organs were investigated. The influence of both metals on dry weight yield was also studied. Concentrations of Pb, Cd and Ca were measured in 15 mm-long apical root segments as well as in whole mesocotyls and coleoptiles after 24 h of incubation of seedlings in hydroponic solutions. It was observed that in Pb- or Cd-treated maize seedlings the dry weight of root apical segments was markedly increased, whereas in the shoots it was less affected. It was also found that the content of both metals in maize seedling organs rose with increasing concentrations of Pb or Cd in the hydroponic solutions. The highest concentrations of both metals were observed in roots, in which the accumulation of Pb was 10-fold higher than that of Cd. By contrast, higher accumulation of Cd than Pb was found in mesocotyl and coleoptile. These data suggest that the mechanisms of Pb and Cd translocation from roots to shoots are different and that the accumulation of Ca in roots and its translocation to shoots was less affected by Pb than Cd.