الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The present study was conducted during the two successive growing winter seasons of 2010/ 2011 and 2011/2012 under greenhouse conditions at the Experimental Station, Faculty of Agriculture, Zagazig University, Sharkia Governorate, Egypt to study the response of wheat plants (Triticum aestivum L.) cv. Sakha 93 to different levels of foliar application of antitranspirants as Kaolin (Ka) at 4 and 6%, Magnesium carbonate (MgCO3) at 6 and 10 % and Fulvic acid (FA) at 160 and 320 ppm, on morphological criteria, some physiological and biochemical processes, anatomical structure and yield and its components as well as the effect of leaf rust pathogen on wheat plant growth under water stress conditions. Data revealed that, all vegetative growth criteria of wheat plants, expressed as plant height (cm), total leaf area/plant (cm2), number of leaves/plant, dry weight (g) of different plant organs were significantly decreased under water stress which was imposed at different growth stages. Meanwhile, foliar application with Kaolin at 4 and 6%, Magnesium carbonate (MgCO3) at 6 and 10% and Fulvic acid (FA) at 160 and 320 ppm, seemed to overcome the bad effects of water 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 recorded under 65% WHC (W1) and the lowest were obtained under 25% WHC (W3). Although spraying plants with antitranspirants as Kaolin(Ka) at rates 4 and 6%, Magnesium carbonate (MgCO3) at the rate of 6 and 10% and Fulvic acid (FA) at 160 ppm and 320 ppm were 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) and photochemical activity were observed in fresh wheat leaves in response to water stress treatments at different growth stages compared with untreated plants. Instead a major response to water stress, in wheat plants, was the marked increases in the activities of catalase, peroxidase, proline, and phenolic compounds in leaves. Also, application of antitranspirant substances at different concentration significantly increased concentrations of photosynthetic pigments and photochemical activity, and decreased the activities of catalase, peroxidase, phenolic compound and proline in leaves. Using such substances, it can overcome the deleterious effects of water stress compared with the untreated plants. The data indicated that, the anatomical features of wheat plants decreased with increasing water stress levels, meanwhile thickness of scalaranchyma tissue was increased. Foliar spray with Kaolin at the rate of 4 and 6%, Magnesium carbonate at the rate of 6 and 10% and Fulvic acid at 160 and 320 ppm increased all the histological features, while thickness of scalaranchyma tissue was decreased. FA specially at 320 ppm gave the best anatomical features compared to the untreated plants under all tested water levels. Though, it could be concluded that FA generally could be used to minimized harmful effect of drought on anatomical structure of wheat plant. Photographs of transmission electron microscope (TEM) showed that spraying with antitranspirants (Ka at 6%, MgCO3 at 10% and FA at 230 ppm) proved to be more effective that reduced the harmful effect of water stress on chloroplast and mitochondria ultrastructure and lead to increase cell walls thickness Application of antitranspirants substances at higher concentration significantly reduced the number of pustule/cm2 or / and leaf area, size of pustules of Puccinia triticina on seedling stage and adult plants It could be recommended that use of Fulvic acid (FA) at 320 ppm mitigate the negative effects of water stress on growth criteria, some physiological and biochemical processes, anatomical structure, yield and its components as well as leaf rust disease incidence of wheat plants.