| Abstract: |
The present study was conducted during the two growing winter seasons of 2008/ 2009 and 2009/2010 under green-house conditions at the Experimental Station, Faculty of Agriculture, Zagazig University, Sharkia Governorate, Egypt to investigate the response of wheat plants (Triticum aestivum L.) cv. Sakha 94 to different levels of foliar application of two types antioxidants i.e., ascorbic acid (AA), salicylic acid( SA) at (0.0, 100, 200 and 400ppm) on plant growth criteria, some physiological and biochemical analysis , anatomical structure as well as yield and its components under drought stress conditions.The data indicated that, all vegetative growth criteria of wheat plants, expressed as plant height (cm), number of tillers/plant, total leaf area/plant (cm2), number of leaves/plant, dry weight (gm) of different plant organs were significantly decreased under drought stress which was imposed at different growth stages. Meanwhile, the foliar application with Salicylic Acid at 200ppm and Ascorbic Acid at 400ppm seemed to overcome the bad effects of drought stress on the above mentioned characters of wheat plants.Yield and its components i.e., number of spikes/plant, number of grains/ spike, number of grains/plant , dry weight of grains /plant (g) and 1000-grains weight (g) were significantly decreased by drought stress and the highest values were obtained under DS1 (70% W.H.C.) and the lowest were obtained under DS3 (30% W.H.C.), although spraying plants with antioxidants i.e., SA at 200ppm and AA at 400ppm was helpful in improving plant yield but was still lower than optimum.A highly significant decrease in the concentrations of photosynthetic pigments (chl.a, chl. B, chl.a+b and caroteniods); photochemical activity was observed in fresh wheat leaves in response to drought stress treatments at different growth stages compared with untreated plants. Instead a major response to drought stress, in wheat plants, was the marked increases in the activities of Catalase, Superoxide dismutase, Ascorbate Peroxidase, Proline, and phenolic compounds in leaves.Also, the application of antioxidants significantly increased in the concentrations of photosynthetic pigments, photochemical activity, and activities of Catalase, Superoxide dismutase, Ascorbate Peroxidase in leaves. It can overcome the deleterious effects of drought stress compared with the untreated plants.It could be recommended the use of SA at 200ppm and AA at 400ppm to mitigate the negative effects of drought stress on growth criteria as well as yield and its components of wheat plants.
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