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The objectives in this study were to investigate some important agricultural traits, their direct and indirect effect on grain yield and to see how these traits are effected by drought. Twenty-six genotypes were planted in two dry and irrigated conditions and in a randomized complete block design. The study was conducted in the agricultural field Faculty of Agriculture, Tehran University. Twenty-one morphologic traits were assessed. The difference of all traits among genotypes was significant. Drought stress caused decrease in days to maturity, plant height, peduncle length, leaf number per plant, grain yield per plant, thousand-kernel weight as well as harvest index, but for other traits the effect wasn’t significant. Grain yield was observed to have a high and positive correlation with plant height, peduncle length, spikelet number, leaf number, biomass, main spike weight, total weight of spikes, average number of kernel per spike, thousand kernel weight, straw yield and harvest index. Linear multiple regression showed that the traits: biomass, straw yield, harvest index, average number of kernel per spike, thousand kernels weight and days to heading (in the irrigated conditions) could explain almost 98.8 percent of the grain yield per plant trait variation. On the other hand, in dry conditions five traits of: average number of kernel per spike, thousand kernels weight, biomass, straw yield and harvest index explained nearly 97.7 percent of the grain yield per plant variation. Results in path analysis in the irrigated condition showed that the direct effects of two traits, namely biomass and harvest index on grain yield per plant, were high and positive. Indirect effects of traits on each other were very low with only indirect effects of two traits: average number of kernel per spike and straw yield on the grain yield per plant being were high and positive. In dry conditions biomass was observed to have the most direct effect on grain yield per plant. Other traits’ direct effects on the grain yield per plant were of no significance. But except harvest index, an indirect effect of other traits (average number of kernel per spike, thousand kernel weight and straw yield) on the grain yield per plant via biomass was high and positive. Based on the obtained results it can be suggested that traits: biomass, average number of kernel per spike, thousand kernel weight, straw yield and harvest index can be indices of cultivar selection for high grain yield in the stress and non-stress conditions. However the effects of these traits in the dry and irrigated conditions were not similar. The strength of biomass and straw yield is less in dry condition.