Abstract
The aim of this study was to test the potential of the brown marine macroalgae, Padina pavonia for reducing the growth inhibition of Zea mays L. induced under 100 mu M Cd+2 or 150 mu M Ni+2 stresses. The impact of Padina pavonia was studied comparing to two well-known plant growth modulators; ascorbic acid and cysteine. Cadmium treated roots showed a significant decrease in Ca+2, Fe+2, Na+ and Zn+2 contents while an increase in Pb+2 content compared to control roots. However, shoots treated with Cd+2 accumulated Fe+2 and Pb+2 while induced a decrease in Cu+2 and Zn+2 contents. For Cd+2 treated roots: cysteine was the most effective modulator for Ca+2 and Fe+2 while Padina pavonica was for Na+ and Pb+2 whereas ascorbic acid was the most effective one for recovering Ca+2, Pb+2 and Zn+2 contents in maize shoots. Roots treated with Ni+2 showed a significant decrease in Ca+2, Cu+2, Fe+2 and Na+ contents while an increase in Pb+2 and Zn+2 contents compared to control roots. However, shoots treated with Ni+2 accumulated Cu+2 while induced a decrease in Ca+2, Fe+2, Na+, Pb+2 and Zn+2 contents. In addition, cysteine was the effector for the recovery of Fe+2, Na+ and Pb+2 concentrations in Ni+2 treated roots and Na+ and Zn+2 in Ni+2 treated shoots. For Padina pavonica, it recovered Ca+2, Pb+2 effectively in Ni+2 treated shoots only. For ascorbic acid, it recovered: Cu+2 roots and shoots, Ca+2 roots and Fe+2 shoots. We conclude that Padina pavonica is an effective bioremediator for Cd+2 and Ni+2 stresses.