الفهرس 
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Abstract
The present study was carried out at Mansoura University, Faculty of Agriculture, Agronomy Department Farm, Dakahlia Governorate, Egypt, during the two seasons 2013/2014 and 2014/2015 seasons using six parental bread wheat cultivars (Triticum aestivum L.). These genotypes were Giza 168, Sakha 93, Shandweel 1, Gemmeiza 12, Sids 14 and Misr 2. All possible parental combinations without reciprocals were made among the six varieties, giving 15 crosses. The results indicated clearly that mean squares of genotypes were highly significant for all studied traits at both normal and stress conditions. Mean squares of GCA and SCA were significant or highly significant for most of studied traits at both normal and stress conditions, The significance of GCA and SCA indicate the presence of both additive and non-additive types of genes in the genetic system controlling these traits.The water stress treatment decreased significantly the mean of all studied flowering, vegetative, physiological yield and its components traits.The obtained results revealed that all studied traits i.e. flowering, vegetative, physiological yield and its components and quality traits were significantly affected by different wheat genotypes (parents and its crosses)Based on general combining ability estimates, the best combiners at normal and water stress conditions for days to heading and flowering (earliness) were P1 (Giza 168) and P2 (Sakha 93); for tillers/plant was P5 (Sids 14); for plant height were P1 (Giza 168), P2 (Sakha 93) and P4 (Gemmeiza 12); for chlorophyll content was P1 (Giza 168); for flag leaf area was P3 (Shandweel 1) at stress condition; for spike length was P3 (Shandweel 1) at water stress condition; for spikelets No. /spike was P6 (Misr 2); for grains number/spike was P4 (Gemmeiza 12) at normal condition; for spikes number/plant was P6 (Misr 2) at normal irrigation condition and P5 (Sids 14) at stress condition; for dry weight of plant at flowering stage was P5 (Sids 14); for 100- kernel weight were P2 (Sakha 93), P5 (Sids 14) and P6 (Misr 2) at water stress condition; for biomass yield per plant was P6 (Misr 2); for grain yield / plant was P3 (Shandweel 1); for oil % was P6 (Misr 2); and for crop growth rate was P6 (Misr 2).1-P2 (Sakha 93) and P3 (Shandweel 1), crosses: P3xP5, P3xP6, P2xP6, P3xP4 and P2xP3 were the highest tolerance to water stress, where they had low drought susceptibility index, therefore these genotypes can be used in breeding program and wheat improvement of resistance to drought.