Now days, production of drought tolerance varieties is an important interest in plant breeding programs. This study was conducted to investigate evaluation of twenty seven different of wheat ( 9 lines), triricale ( 5 promising lines) and tritipyrum (13 lines) under drought stress under two levels of irrigation (non stress and drought stress) as a completely randomized block design with three replications in 2014-2015. Morphological, physiological and phonological trait were recorded. The results of descriptive statistics for morphological, physiological and phenological traits showed that the mean of all studied traits except number of days to 100% emergence, chlorophyll (a), chlorophyll (b) and carotenoied were significantly greater in normal than drought stress conditions. Also it appeared that phenotypic coefficients were more than the genetic coefficients in all traits, except number of days to 100% emergence , indicating the high effect of environmental conditions on studied traits. The analysis of variance for different characters under two environments (non stress and drought stress) indicated highly significant differences among treatments for all genotypes studied. Also combined analyses of variances indicated significant genotype× environment interaction for day to 50% pollination, chlorophyll (a), chlorophyll (b) , carotenoied, numbers of tillers per plant, spike length, seed weights per spike, number of spikes per plot, number seed per spike, seed weight and seed yield as a different function of genotypes to stre and non- stress conditions. There was a high positive and significant correlation between yield and seed weights per spike and number seed per spike in both conditions. The stepwise multiple linear regression analysis indicated that biological yield, number seed per spike and 1000 seed weight explained 82 (%) of the total variance under normal condition. Also regression analysis showed that biological yield, seed weights per spike, number seed per spike and 1000 seed weight had the most effect on seed yield under drought stress.. Principal component analysis (PCA) revealed that the the three and four components had the highest direct effect on grain yield in drought and normal stress, respectively, which explained 70(%) of the total variations of seed yield. Cluster analysis Keywords: Cereal, Drought tolerance index, Drought Stress,Yield.
