الفهرس 
Physiological and genetic studies on wheat plants growing under drought stress conditions
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Abstract
Cereals are among the most important food plants worldwide, and wheat is essential to global food security in all countries. Here, two population of spring and winter wheat, the first being the Egyptian spring wheat landraces and consisting of 125 genotypes. This experiment was conducted to estimate the response of the population under normal conditions and drought stress by evaluating the relevant morphological characteristics, plant height, flag leaf area, spike length, number of spikelets, and stress tolerance index. Our results showed that drought treatment had a significant inhibitory effect on the morphological characteristics of some wheat genotypes. However, these genotypes differed in their response to drought stress and drought-sensitive genotypes showed a greater reduction in plant height, flag leaf area, spike length and number of spikelets compared to tolerant genotypes. There was a significant effect between genotypes and treatments for all studied traits. For each phenotypic trait, each genotype showed significant differences from each other. According to the results from the previous experiment, we selected 10 accessions representative genotypes from high to low tolerance to estimate the morphological, physiological and biochemical level under normal conditions and drought stress. Then many traits were evaluated at the morphological level such as fresh weight, dry weight, plant length, flag leaf area, thousand grain weight and grain yield. Also, at the physiological and biochemical level, the measured trait are concentration of chlorophyll, the concentration of elements (potassium, calcium, magnesium and sodium), total sugars, proline concentration, total protein, peroxide enzyme and total phenol concentration. The results showed that L8 and L10 were the most tolerant genotypes, which had the highest weight of thousand grains and grain yield. On the other hand, L1, L2 and L3 genotypes were the most sensitive to drought. Moreover, the Egyptian wheat was also tested to study the effect of wheat on the development of the spike. Our results indicated that drought affects the length of the growth stages of the spike and reduces the potential of the grain yield. Another population of winter wheat, consisting of 260 genotypes collected from all over the world, was studied to determine the genes potential drought stress tolerance in germination and seedling stages using genome-wide association mapping and identification of 106 potential candidate genes in wheat.