In order to evaluation of drought resistant indices in barley (Hordeum vulgare L.), 10 barley genotypes evaluated in Completely Randomized Design with three Replications in two conditions, (under drought stress and in normal with irrigation in planting, flowering and grain filling stages) in Islamic Azad University, Miyaneh Branch Research Farm in 2012. Drought tolerant indices basis of yield performance in drought (Ys) and normal (Yp) environments such as Mean productivity (MP), Stress tolerance (TOL) Geometric mean productivity (GMP), Stress Susceptibility index (SSI) and Tolerance index (STI) and eight main crop parameters such as plant height, spike height, number seed per spike, number tiller, 100 seed weight seed yield, biomass yield and harvest index were calculated. Results showed that the difference among the majority of traits in both normal and under drought conditions was significant. Mean comparison displayed that the value of all traits under drought condition in compare with normal condition was decreased. By the way, the highest value of spike height, the number of seeds per spike, seed yield and biomass yield in both drought and normal condition devoted to genotypes number 9 and 2 respectively. Based on Drought tolerant indices the highest amounts of STI, GMP and MP were related to genotypes of Gkomega/cab117-5-9- 5//Sararood/….. and Yesevi-93/6/Tokak/3/BK…. in both under drought and normal conditions. Correlation analysis between seed yield and all indices revealed that there are positive and significant relationship among STI, GMP, MP and seed yield in both under drought and normal conditions. Therefore, STI, GMP and MP are the best indices for screening drought tolerant genotypes in barley. Cluster analysis based on GMP, MP and STI indices divided 10 genotypes of barley in to two main resistant and sensitive groups. Drought tolerant genotypes were number 2 and 9.
