Investigation of physiological effects of heavy metal stress on some barley (Hordeum vulgare L.) cultivars

The aim of this study is to investigate responses of two barley (Hordeum vulgare L.) genotypes (Tarm ? 92 and Tokak 157/37) subjected to cadmium (0 ? 1 ? 1,5 mM) and lead (0 ? 10 ? 15 mM) stress. Cadmium treatments decreased photosynthetic pigment (chlorophyll a, total chlorophyll and total carotenoid) contents in leaves of Tarm-92 while lead was more effective in Tokak 157/37. Both cadmium and lead increased total phenolic content in leaves of Tokak 157/37. Malondialdehyde accumulation was more significant in Tarm-92 leaves as the result of cadmium and lead application. Hydrogen peroxide content was lower in cadmium-treated Tarm ? 92 leaves while it was increased as the result of lead application. Both cadmium and lead treatment decreased ascorbate peroxidase activity in Tarm ? 92 and Tokak 157/37 leaves while guaiacol peroxidase activity was increased. Glutathione reductase activity in cadmium and lead - treated leaves of Tarm ? 92 was lower while it was increased in Tokak 157/37.As a result, it may be concluded that Tokak 157/37 can protect itself oxidative stress derived from high cadmium concentration and it is more sensitive to lead toxicity.