Emmer wheat (Triticum dicoccon Schrank) is the allo-tetraploid progenitor of the modern wheat and holds genetic variation for tolerance to drought. Water use efficient emmer wheat genotypes are considered better maintainers of yield under water limited environments. However, existing genetic variation for water use efficiency (WUE) in emmer germplasm has not been fully explored nor are the underlying mechanisms of this trait properly understood. Three field selected, contrasting emmer wheat genotypes were assessed at 90% and 50% pot soil water capacity (PSWC) in quadruplicated design for water use response under glasshouse conditions. Significant differences were observed between water treatments and among genotypes for various traits including carbon isotope discrimination (CID) and the grain yield. Water stress had significant negative impact on grain yield but less so in genotypes superior in water use efficiency. The relationship between grain yield and WUE was positive both at 90% and 50% PSWC. Genotypes with lower CID scores had higher WUE and grain yield under water stress. The genetic variation for WUE observed in emmer wheat is a potential resource to improve drought tolerance in hexaploid wheat.

二粒小麦（Triticum dicocconSchrank) 是现代小麦的异源四倍体祖先，具有耐旱性的遗传变异。水分利用效率高的二粒小麦基因型被认为是在水分有限的环境下更好的产量保持者。然而，二粒种质中水分利用效率 (WUE) 的现有遗传变异尚未得到充分探索，该性状的潜在机制也没有得到正确理解。在温室条件下的用水响应的四重设计中，在 90% 和 50% 盆栽土壤持水量 (PSWC) 下评估了三个田间选择的对比二粒小麦基因型。在不同的水处理和基因型之间观察到显着差异，包括碳同位素鉴别 (CID) 和谷物产量。水分胁迫对谷物产量有显着的负面影响，但对水分利用效率较高的基因型影响较小。PSWC 为 90% 和 50% 时，谷物产量和 WUE 之间的关系均呈正相关。CID 评分较低的基因型在水分胁迫下具有较高的 WUE 和谷物产量。在二粒小麦中观察到的 WUE 遗传变异是提高六倍体小麦耐旱性的潜在资源。