Exogenously-applied Salicylic Acid and Ascorbic Acid Modulate some Physiological Traits and Antioxidative Defense System in Zea mays L. Seedlings under Drought Stress

THIS WORK was undertaken to evaluate the effects of salicylic acid (SA) (0.0 and 0.5 mM) and ascorbic acid (AsA) (0.0 and 100 ppm) on enzymes activity, soluble sugars, and some physiological traits of maize seedlings (Zay mays L.) under drought stress using PEG-6000. In general, under drought conditions, significant reduction in plant biomass and photosynthetic pigments was detected. On the other hand, soluble sugars (glucose, fructose and sucrose), soluble proteins, antioxidant enzymes activity [catalase (CAT), ascrobate peroxidase (APDX) and superoxide dismutase (SOD)], glutathione (GSH), proline and malondialdehyde (MDA) contents were increased significantly under drought as compared to control. Shoots of tested plants were more affected by drought stress than roots. Seed presoaking in AsA or SA solutions resulted in massive increase in growth parameters, chlorophyll contents, osmoprotectants (soluble sugars, free amino acids and soluble proteins), antioxidant enzymes activity [ascrobate peroxidase (APDX) and superoxide dismutase (SOD)] and non-enzymatic antioxidants [carotenoids, and glutathione (GSH)] content as compared to control. Conversely, proline, catalase (CAT) and malondialdehyde (MDA) content were decreased significantly. The present study established that, both salicylic acid and ascorbic acid alleviate drought stress in maize plants which could attribute to the increased in osmotic solutes and antioxidative capacity of maize plants.