In order to evaluate most important traits affecting grain yield of ten barley genotypes under stress and nonstress conditions, a field experiment was conducted similarly in 2010-2011, at University research farm of Karaj Azad Islamic (35º 43´ N latitude, 50º 56´ E longitude, 1160 m altitude). The experiments were laid out in split plot using randomized complete block design with four replications. Main plots were in two levels; full irrigation and drought stress (terminal irrigation at ear

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... arance). Ten barley genotypes also used as sub plot treatments. There were significant correlation among grain yield, fertile tillers number, days to maturity, thousand grain weight, straw yield, biomass and harvest index also inoculated days to heading negatively in two conditions. Results of stepwise regression revealed that 4 traits: fertile tillers number, harvest index, Biomass and straw yield (in the irrigated condition) could explain almost 98 percent of grain yield trait variation. Results of path analysis showed that inoculated biomass had the most direct effect (1.73) on grain in stress condition. Based on obtained results it can be suggested these traits: fertile tillers number, biomass and straw yield in stress and non-stress conditions.