Effect of 2,4-Dichlorophenoxy Acetic Acid on Antioxidant Systems in a Non-Target Plant (Zea mays L.)

This work aimed to study the impact of various concentrations of the herbicide 2,4-D dichlorophenoxyacetic acid (2, 5, 10 mg L-1) on fresh and dry biomasses, photosynthetic pigments, quantum yield of PSII (Fv/Fm) and oxidative stress parameters on 28-day old Zea mays leaves. Foliar application of a low dose of 2,4-D significantly promoted the growth biomarkers, whereas, the high doses induced severe disturbances and reduced the growth attributes. This situation produced over-accumulation of hydrogen peroxide (H2O2) and lipid peroxidation (MDA) and that was accompany with a significant increase in activity of superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PDH). Otherwise there was a significant decline in ascorbate peroxidase (APx), guiacol peroxidase (GPX), glutathione peroxidase (GSHPx) and glutathione reductase (GR). Moreover, a significant decline of glutathione (reduced form; GSH) and ascorbic acid (AsA) contents, glutathione redox potential (GSH/GSSG), NADPH and NADPH/NADP+ ratios were recorded. These observations might indicate that high doses of 2,4-D caused a menace to non-target plants through the disruption of antioxidant systems.