الفهرس 
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Abstract
This study was carried out at the Experimental Farm in Agronomy Department, Faculty of Agriculture, Mansoura University during the two seasons 2012/2013 and 2013/2014 using six diverse barley genotypes (Hordeum vulgare L.). All possible parental combinations without reciprocals were made among the six genotypes, giving 15 crosses. The six parental genotypes and 15 F1’s were evaluated in two experiments. The first experiment, was irrigated with the recommended treatment i.e three irrigations after planting irrigation (normal condition), and the second one was irrigated with planting irrigation only (drought condition). Days to heading, days to maturity, grain filling period, grain filling rate, number of tillers per plant, flag leaf area, total chlorophyll content, Plant height, spike length, number of grains/spike, number of spikes/plant, 100–grain weight and grain yield /plant were studied. Statistical analysis revealed highly significant effects of genotypes under the two conditions for all traits, providing evidence for presence of large amount of genetic variability, which considered adequate for further biometrical assessment. Significant or highly significant differences for all studied traits were found at the two conditions.Water stress condition decreased the means of all studied traits for parents and their crosses. The results of combining ability analysis of cultivars can be used in hybrid breeding program to facilitate the breeder’s decision when they are selecting the cultivars. This index was used to estimate relative stress injury because it accounted for variation in yield potential and stress intensity. This index could be estimated based on many traits. The results showed that grain yield plant-1 showed negative correlation with all earliness traits. Expected grain filling rate showed that positively and high significant correlation. Data showed that the genetic variance was higher than environmental variance for all studied traits at both normal and stress conditions, except grain filling rate under water stress condition.Broad sense heritability showed high percentages for all studied traits and narrow sense heritability percentages varied from low to moderate. These results indicate that genotypic variances played the major part of phenotypic variances.