Abstract
Solidago canadensis L. cv. ʽTaraʼ as important flower production and traditional medicine. Heavy metals such as lead (Pb) have harmful effects on ornamental plants. So, this study aimed to reduce the toxic effect of Pb on Solidago canadensis plant through spermine(SPM) application. Plants were grown in treated soils with different Pb levels (0, 400, and 800 ppm) and sprayed with spermine at 0, 1 and 2 mM. Plant height, leaf number, total leaf area, stem diameter, number of inflorescences, length of inflorescences stem, fresh & dry weights of shoot, root & inflorescences and flowering period were recorded as growth characters. Photosynthetic pigments, antioxidant enzymes, total sugars, total soluble phenols, total free amino acids, proline, minerals (N, P, K, Pb) and protein as chemical contents. Results showed that Pb at 800 ppm resulted in the lowest values for most tested characteristics, but increased Pb level in shoots and roots. Spermine treatments especially 2mM were highly significant in most characteristics under Pb conditions, except Pb concentration reduction as compared to the control. Results provided evidence that spermine minimized the adverse effects of lead (Pb) stress and could play an essential role in providing stress tolerance.