CADMIUM AND LEAD EFFECTS ON GROWTH PERFORMANCE OF ZINNIA ( <i>ZINNIA MARYLANDICA</i>)
The effects of heavy metals Cd and Pb on the growth and development of Zinnia marylandica, cv. ‘Zahara Yellow’ were studied. The plants were grown on substrate contaminated with Cd and Pb at levels below, at the maximum limited concentration (MLC) and several times higher than it. In presence of Cd, stem length increased over the non-treated plants whereas plant width was enhanced only at Cd MLC. Lead did not affect these indices. Both at Cd and Pb the appearance of but formation and flowering did not differ from the control. However, at Cd concentrations exceeding MLC more than 25 times and Pb higher than MLC, a deviation of the stem growth from the normal vertical direction did occur. In plants subjected to Pb above MLC a discoloration of flower petals was observed. These caused overall deterioration of the ornamental quality. The results suggest that the studied zinnia genotype expresses tolerance to relatively high Cd concentration and is sensitive to more severe Pb stress.