The effects of heavy metals on the seed germination and seedling growth of two endemic Verbascum species

Abstract

In this study, we aimed to investigate the effects of heavy metals (Cd, Cu, Cr, Ni and Zn) on seed germination and seedling growth of two endemic Verbascum species, V. bombyciferum Boiss. and V. olympicum Boiss. We determined the root and shoot elongation, seed germination percentage, mean germination time (MGT), seed vigour index (SVI) and metal tolerance index % (MTI). These species have been defined as a pioneer and dominant species of ruderal plant communities in disturbed areas, such as roadsides, developed building areas, rubber hips, and mining areas at different altitudes on Uludag Mountain. Seed germination was reduced significantly in V. olympicum with increased metal concentrations (P < 0.05). However, only Cd and Cr resulted in significantly decreased seed germination in V. bombyciferum (P < 0.05). MGT was also altered by metal treatments in both species. Although the metal treatments resulted in root growth inhibition, shoot growth was not inhibited. SVI and MTI were also negatively affected by treatments.