The present study aims to evaluate the comparative effects of
methyl parathion and
hexaconazole on genotoxicity, oxidative stress, antioxidative defence system and photosynthetic pigments in barley (Hordeum vulgare L. variety karan-16). The seeds were exposed with three different concentrations, i.e. 0.05, 0.1 and 0.5 % for 6 h after three pre-soaking durations 7, 17 and 27 h which represents G1, S and G2 phases of the cell cycle, respectively. Ethyl methane sulphonate, a well-known mutagenic agent and double distilled water, was used as positive and negative controls, respectively. The results indicate significant decrease in mitotic index with increasing concentrations of pesticides, and the extent was higher in
methyl parathion.
Chromosomal aberrations were found more frequent in
methyl parathion than
hexaconazole as compared to their respective controls. Treatment with the pesticides induced oxidative stress which was evident with higher contents of H2O2 and lipid peroxidation, and the increase was more prominent in
methyl parathion. Contents of total phenolics were increased; however, soluble
protein content showed a reverse trend. Among the enzymatic
antioxidants, activities of
superoxide dismutase and
peroxidase were significantly up-regulated, and more increase was noticed in
hexaconazole. Increments in total
chlorophyll and
carotenoid contents were observed up to 0.1 % but decreased at higher concentration (0.5 %), and the reductions were more prominent in
methyl parathion than
hexaconazole as compared to their respective controls.
Methyl parathion treatment caused more damage in the plant cells of barley as compared to
hexaconazole, which may be closely related to higher genotoxicity and oxidative stress.