Effect of calcium and cadmium on growth and accumulation of cadmium, calcium, potassium and sodium in maize seedlings

We examined cadmium (0.1 mmol/l) toxicity and effect of different calcium concentrations (0.1, 1.0, and 10.0 mmol/l) on the growth of organs (root, mesocotyl and coleoptile) of 4-day-old maize seedlings in hydroponic cultures. The influence of both metals on distribution of cadmium, calcium, potassium and sodium in the organs of maize seedlings was also studied. Calcium at a concentration of 1.0 mmol/l increased the growth of all organs in comparison with the growth in 0.1 and 10.0 mmol/l CaCl₂. Cadmium inhibited maize organ growth in the presence of 0.1 and 1.0 mmol/l CaCl₂, whereas cadmium toxicity was not observed at 10.0 mmol/l CaCl₂. It was found that the content of both metals in maize seedling organs rose with increasing concentrations of Ca or Cd in the hydroponic solutions. Cadmium administration together with 10.0 mmol/l CaCl₂ led to an increase in calcium concentrations in roots and coleoptiles. The highest calcium concentration (10.0 mmol/l) caused a decrease in the cadmium concentration in roots. The addition of cadmium with 0.1 or 1.0 mmol/l CaCl₂ diminished potassium accumulation in the roots. By contrast, potassium content in the roots was not altered by cadmium when calcium was applied at a concentration of 10.0 mmol/l CaCl₂. Sodium content in maize seedlings was not affected in the presence of both cadmium and calcium at a concentration of 0.1 or 1.0 mmol/l, whereas cadmium with 10.0 mmol/l CaCl₂ decreased sodium accumulation in the roots. Thus, we conclude that the positive effect of highest concentration of calcium on the growth in the presence of Cd relay on the maintenance of high concentration of potassium in the roots.