Impact of Heavy Metal Stress on In Vitro Seed Germination and Seedling Growth Indices of Two Turfgrass species

Turfgrass is one of the important components of ornamental plant in the construction of parks and landscapes so that the purpose of this study was to investigate the influence of type and different concentrations of Copper, Zinc and Cobalt on germination and seedling growth of perennial ryegrass (Lolium perenne L.) and red fescue (Festuca rubra L.) seeds in in vitro conditions. This study was carried out in 2014. A factorial experiment was conducted based on a completely randomized design with three replications in laboratory. Seeds were sown in the sterilized medium containing 7 g/L of agar under the laminar air flow. Then, three solutions of ZnSO4, CuSO4 and COCl2 in five concentrations of 0, 20, 50, 100 and 200 mg/L were prepared. Seeds were placed in the incubator at 24°C and 50% humidity for 25 days. Seed germination traits and seedling growth were recorded. Results showed that zinc and copper had minimum and maximum inhibitory effects on seedling growth, respectively. At the presence of copper, by increasing the concentration from 0 to 200 mg/L, the germination and seeding growth were sharply reduced. Inhibitory effects on seedling growth were found in higher concentrations than 50 mg/L at the presence of zinc and cobalt metals. The minimum rate of germination and seedling growth in both red fescue and perennial ryegrass was observed in the concentrations of 20 to 200 mg/L of copper. Therefore, perennial ryegrass and red fescue as turfgrass cannot germinate and grow in soils with copper contamination even at low concentrations, but they can tolerate moderate concentration zinc and particularly cobalt contamination in the polluted environments.