Evaluation of Cd effects on growth and some oxidative stress parameters of wheat cultivars during seedling stage

Regarding negative effects of Cd on wheat growth, it seems that evaluation of wheat cultivars behaviors in response to Cd existence is necessary. In this regard, six different cultivars of wheat were selected and cultivated by aeroponic system. Then they were treated by 200 mM cadmium chloride for 14 days since they have reached 3 or 4 leaves stage. Finally, plants were sampled and morphological characteristics, parameters subjected to defense mechanisms as well as amount of accumulated Cd in tissues were evaluated. The results showed that cadmium accumulation in tissues significantly decreased root length and dry matter of root, shoot and whole plant. Cd accumulation also increased hydrogen peroxide amount in leaf cells of Kohdasht and Pishtase cultivars. However, lipid peroxidation was noticed in Izengeran cultivar as well as two previously mentioned cultivars. The reduced activities of glutathione
S-transferase, catalase and ascorbate peroxidase enzymes are probably the main reasons of the lipid peroxidation increase in Kohdasht cultivar. However, there was no damage on membranes of Izengran and Pishtase cultivars, which indicates the balance between production and scavenging of damaging factors of these cultivars. Generally, it can be stated that available Cd in medium was adsorbed and accumulated in wheat leaves resulting in reduction in dry matter of different parts and whole seedling of wheat which is due to susebtability of different cultivars to Cd. However, there were no oxidative stresses in leaves of Gaskogen, Agosta and MV17 cultivars due to their better defense mechanisms.