Breeding for drought tolerance is the most effective approach to mitigate drought effects. The prime goal of the current study was to identify potentially drought-tolerant wheat (Triticum aestivum L.) genotypes. Therefore, an extensive collection of wheat genotypes (2,100) was evaluated under two water regimes, that is water deficit (WD, 50% ETc ‘crop Evapotranspiration’) and well-watered (WW, 100% of ETc) across several environments in Egypt. The number of days to flowering (NDF), plant height (PH) and grain yield (GY) were recorded under both water regimes across environments. Additionally, three yield-based drought indices and water-use efficiency (WUE) were calculated for the top 30% yielding genotypes (that produced economical GY; 3.58 ton ha⁻¹ for WD and 7.5 ton ha⁻¹ for WW). The results indicated a significant effect for environments, water stress, and genotypes, as well as the second- and third-order interactions across all traits. WD significantly reduced PH, NDF, and GY by 5.0 cm, 10.6 days and 50.0%, respectively. PH, NDF and GY were highly correlated. However, the direction and magnitude of correlation under normal conditions were different from those under WD. For example, under WW conditions, late flowering and taller genotypes tended to produce higher GY. In contrast, under WD, earlier and shorter wheat genotypes tended to produce higher GY. According to the drought tolerance index (DTI), 254 genotypes were considered drought tolerance (DTI > 1). Based on WUE, DTI and GY under WD, 80 genotypes outperformed the commercially grown Egyptian cultivars. Our results implied that the evaluated collection might be a valuable source not only for drought-tolerant genotypes but also for highly yielding water-efficient genotypes under favourable conditions in Egypt and similar geographic regions.

中文翻译：

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对现代和野生小麦收集品施加缺水以识别抗旱基因型

耐旱育种是减轻干旱影响的最有效方法。当前研究的主要目标是鉴定潜在的耐旱小麦 ( Triticum aestivum  L.) 基因型。因此，在埃及的几个环境中，在两种水分状况下评估了大量小麦基因型 (2,100)，即水分不足（WD，50% ETc“作物蒸发蒸腾”）和水分充足（WW，100% ETc） . 在两种不同环境下的水分状况下记录开花天数 (NDF)、株高 (PH) 和谷物产量 (GY)。此外，针对产量最高的 30% 基因型（产生经济 GY；WD 为 3.58 ton ha ^-1和 7.5 ton ha^-1WW）。结果表明对环境、水分胁迫和基因型以及所有性状的二级和三级相互作用都有显着影响。WD 将 PH、NDF 和 GY 分别显着降低 5.0 cm、10.6 天和 50.0%。PH、NDF和GY高度相关。但是，正常情况下相关的方向和幅度与WD下的不同。例如，在 WW 条件下，晚开花和更高的基因型往往会产生更高的 GY。相比之下，在 WD 下，较早和较短的小麦基因型往往会产生较高的 GY。根据耐旱指数（DTI），254个基因型被认为是耐旱（DTI>1）。基于 WD 下的 WUE、DTI 和 GY，80 个基因型的表现优于商业种植的埃及品种。