ORIGINAL ARTICLE

Foliar Ascorbic Acid Alleviates Salt-induced Oxidative Stress in Maize

The effects of the foliar ascorbic acid application on major antioxidant enzymes, photosynthetic pigment content, malondialdehyde, hydrogen peroxide, free proline and the reduced ascorbate were investigated in salt-stressed (75 mM NaCl) maize genotype (ADA 9510). The results showed that salt stress significantly decreased chlorophyll a, chlorophyll b, total chlorophyll, total carotenoid and the reduced ascorbate contents and the activities of superoxide dismutase, ascorbate peroxidase and glutathione reductase. Conversely, malondialdehyde, hydrogen peroxide and free proline contents were increased by salt stress. These results showed that salinity led to the oxidative stress and destruction of photosynthetic pigments in maize leaves. The foliar ascorbic acid application, on the other hand, caused to the increased chlorophyll a and the reduced ascorbate content, elevated level of antioxidant enzymes and decreased malondialdehyde, hydrogen peroxide and free proline content. This kind of changes may indicate that the foliar ascorbic acid application activates the antioxidant defence system and counteract the oxidative stress. Thus, it may be concluded that the foliar ascorbic acid application improves salt tolerance and encourage the growth of maize plants under salt stress.