Drought tolerance in wild species of barley (Hordeum vulgare ssp. vulgare L.) (especially Iranian species) and the relationship of physiological traits with yield indices to explore inter- and intraspecific variation is poorly understood. Drought tolerance of 83 genotypes belonging to 16 species of genus Hordeum were evaluated under normal (well-watered), mild, and intense drought stress conditions during 2012-2014. High inter- and intraspecific variation was observed for yield, physiological traits, and drought tolerance. Proline content was identified as the best physiological index for indirect selection of drought-tolerant genotypes in this study. The same species were grouped together to a great extent based on physiological and morphological attributes. Superior genotypes were characterized within each stress environment. In the wild species groups, three genotypes (Genotypes 40, 44, and 45) from Hordeum murinum and two genotypes (Genotypes 3 and 4) from Hordeum brachyantherum were identified as drought tolerant within both mild and intense drought environments. These genotypes may be used in future studies to characterize genes and mechanisms related to drought stress.

AbstractIn this study, agro-morphological and yield-related traits associated with drought tolerance in 80 barley genotypes belonging to 15 wild species together with the cultivated one, and their potential to improve adaptation to different levels of drought stress conditions (moisture environments) were studied. There was significant genetic variation among the genotypes and species for all of the measured traits, as well as differential responses of genotypes across environments. The results indicated high variation for grain yield (GY) under drought stress among the genotypes, and that some of the wild genotypes had consistently superior specific adaptation to the water stress conditions. The genotypes belong to wild barley species, especiallyHordeum murinumandHordeum marinumhad lower GY but relatively higher yield stability under different environments. Traits such as number of seed per plant and hundred kernel weight were positively correlated with GY in all of the environments. High negative correlation between GY and days to ripening was observed only under intense drought environment, showing drought escape as a strategy of wild plants under highly stressed conditions. Grouping of the genotypes by principal component analysis completely separated cultivated barley and its progenitor (Hordeum vulgaressp.spontaneum) from other wild genotypes; however, the other wild species were slightly separated from each other. In addition, the Iranian and foreign genotypes did not completely separate from each other. The identified wild barley genotypes with favourable characters and high drought tolerance could be used in genetic studies and barley improvement programmes especially for drought stress.