This study was conducted at Research Farm of Isfahan University of Technology to determine relationship between traits and evaluate stress tolerance and susceptibility indices of different barley lines, using a split plot design with three replications in nitrogen stress and non stress conditions. Main plot consisted of non stress (using 50 kg/ha net nitrogen before the beginning of vegetative growth, and 100 Kg/ha net nitrogen at primary stage of vegetative growth, stem enlargement and grain filling) and nitrogen stress (using 50 kg/ha net nitrogen before the beginning of vegetative growth) conditions. Sub plots were 49 recombinant inbred lines derived from the cross of Azummugi (AZ) and Kanto Nakate Gold (KNG) and the parents. The result indicated that there was enough genetic variation for all traits in stress and non stress conditions except 1000-grain weight. Nitrogen stress decreased all the traits except flag leaf width, peduncle weight, ratio of peduncle weight to length, 1000-grain weight, number of grain/spike, grain weight per spike and harvest index. The interaction effect of genotype and nitrogen was considerable for all the traits except days to heading, test weight, and 1000-grain weight. Grain yield had significant positive phenotypic and genetic correlation with biological yield and harvest index. Results of path analysis showed that harvest index had high positive direct effect on grain yield in both stress and non stress conditions. Factor analysis detected 6 factors which explained 78% and 79/32% of the total variation in stress and non stress conditions, respectively. Four factors were important. Flag leaf length, spike length, awn length and peduncle length had higher loads on the first factor in non stress condition. Spike weight, number of grain/spike and weight of grain/spike were more correlated with the second factor. The third factor was correlated with days
