Pot experiments were 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 salicylic acid( SA) at (100, 200 and 400 ppm) on growth criteria, some biochemical analysis i.e. photosynthetic pigments,Photochemical activity, Catalase , superoxide dismutase and Ascorbate Peroxidase activities 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 tiller/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 seemed to partially overcome the harmful 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 control (70% W.H.C.) and the lowest were obtained under DS2 (30% W.H.C.), although spraying plants with antioxidant,SA at 200 ppm was helpful in improving plant yield but was still lower than the control.
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 and Ascorbate Peroxidase in leaves.
Also, the application of salicylic acid( SA) 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 by using antioxidant SA compared with the untreated plants.
Conclusively, it could be recommended the use of SA at 200ppm to partially mitigate the negative effects of drought stress on growth criteriaas well as yield and its components of wheat plants.