الفهرس 
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Abstract
Three sets of experiments (Laboratory, diallel and stability) were conducted at the Faculty of Agriculture, Zagazig University, during the wintersuccessive growing seasons 2012/2013 and 2013/2014 to generate informations about the impact of heavy metals (Zn, Pb and Cd) on seed germination, seedling growth, performance, heterosis, combining ability, genetic behavior and stability of some bread wheat genotypes. The results indicated that heavy metals reduced germination %, seedling growth, while increased phytotoxicity, sensitivity and tolerance indices. The most negative effect was due to the mixture of the three elements followed by Cd, Pb and Zn. The mixture of the three elements reduced number of days to maturity, morpho-physiological characters, spike characteristics, grain yield, protein content in leaves and stems. Otherwise the contents of proline, Zn, Pb and Cd in leaves, stems and grains were increased. Highly significantly negative or positive heterosis and heterobiltiosis were detected for all studied characters. GCA and SCA variances were highly significant for almost studied characters and the ratio of GCA / SCA variances was less than unity in most cases, indicating the predominance of non additive gen action in the heredity of the studied characters reflecting low to moderate narrow sense heritability. The parental genotypes Misr 1 and Sids 12 are suitable for stress conditions, while Line1 was desirable genotype. Environments E8, E4 and E2 were the most differentiating environments, while environments E3, E6 and E7 were less responsive.