نبذة مختصرة : High genetic diversity among ecotypes was observed for most of the important traits related to grain yield. The desired ecotype A19 had the highest, and ecotypes A16 and A17 had the lowest yield and grain yield components. The results of correlation analysis revealed that an array of traits including grain water use efficiency, plant height, harvest index, grain weight per main spike, main spike weight, peduncle weight, spikelets/spike, peduncle length, thousand grain weight, grain filling period length, and main stem weight showed the highest positive and significant correlation (p≤0.01) with grain yield. Additionally, grain yield had the most significant (p≤0.01) and negative correlation with days to heading, water consumption, days to anthesis, root dry weight, and days to maturity. According to the stepwise regression results, water use efficiency, grain weight per main spike (both with a positive regression coefficient), and root dry weight (with a negative regression coefficient) were identified as the most important traits influencing grain yield variations. Water use efficiency had the highest direct positive effects on grain yield, while grain weight per main spike and root dry weight had the highest indirect positive and negative effects on grain yield, respectively, through increasing and decreasing water use efficiency. Therefore, it may be infered that due to the relative similarity of the genetic background of common bread wheat with Aegilops tauschii species, as one of its wild ancestors, the selection for higher grain water use efficiency and grain weight in the main spike, as well as root and phenological traits (except grain filling period) leads to the improvement of common wheat yield in normal moisture conditions. Ecotypes A16 and A17 were identified as the most unfavorable ecotypes, mainly because they needed greater number of days to heading, days to pollination, and days to physiological maturity, and invested more photosynthetic products to rooting attributes, including root dry weight. According to the results of this research, Aegilops tauschii, is an important gene reservoir for improving wheat yield. In this research, ecotype A19, where its higher amounts of grain yield and related traits, including water use efficiency and grain weight in the main spike are accompanied by lower amounts of phenological traits as well as lower dry weight of roots, was the most desirable ecotype. Conclusion Water use efficiency, grain weight per main spike and root dry weight were identified as the most important traits affecting grain yield. Therefore, it may be possible to select for higher values of water use efficiency and grain weight per main spike and lower values of phenological traits and root traits. These traits, which have high heritability and respond well to selection, can be used to identify ecotypes of this wild wheat. Ultimately, they can be used in future wheat breeding programs. [ABSTRACT FROM AUTHOR]
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