Table_1_Screening of Worldwide Barley Collection for Drought Tolerance: The Assessment of Various Physiological Measures as the Selection Criteria.xlsx

Drought is a devastating environmental constraint affecting the agronomic production of barley. To facilitate the breeding process, abundant germplasm resources and reliable evaluation systems to identify the true drought-tolerant barley genotypes are needed. In this study, 237 cultivated and 190 wild barley genotypes, originating from 28 countries, were screened for drought tolerance under the conditions of both water deficit and polyethylene glycol (PEG)-simulated drought at seedling stage. Drought stress significantly reduced the plant growth of all barley genotypes, but no significant difference in drought-induced reduction in the performance of barley seedlings was observed under these two drought conditions. Both cultivated and wild barley subspecies displayed considerable genotypic variability in drought tolerance, which underpinned the identification of 18 genotypes contrasting in drought tolerance. A comparative analysis of drought effects on biomass, water relation, photosynthesis, and osmotic adjustment was undertaken using these contrasting barley genotypes, in order to verify the reliability of the screening and to obtain the credible traits as screening criteria of drought tolerance in barley. As expected, the selected drought-tolerant genotypes showed much less reduction in shoot biomass than drought-sensitive ones under water deficit, which was significantly positively correlated with the results of large-scale screening, confirming the reliability of the screening for drought tolerance under two drought conditions in this study. Likewise, the traits of water relation, photosynthetic activity, and osmotic adjustment differed greatly between the contrasting genotypes under water deficit stress, and they were highly correlated to the growth of barley seedlings, suggesting the potential of them to be the selection criteria for drought tolerance. The analysis of the variable importance of these traits in drought tolerance indicated that sap osmolality and relative water content in the youngest fully-expanded leaf are the suitable selection criteria of screening for drought tolerance in barley at seedling stage.

干旱是一种灾难性的环境限制，严重影响了大麦的农艺产量。为促进育种过程，需要丰富的种质资源和可靠的评估系统来识别真正的耐旱大麦基因型。在本研究中，对来自28个国家的237个栽培和190个野生大麦基因型进行了筛选，以评估其在幼苗期水分缺乏和聚乙二醇（PEG）模拟干旱条件下的耐旱性。干旱胁迫显著降低了所有大麦基因型的植物生长，但在两种干旱条件下，耐旱性诱导的大麦幼苗性能下降并无显著差异。栽培和野生大麦亚种在耐旱性方面表现出显著的基因型变异，这为鉴定18个耐旱性差异显著的基因型奠定了基础。利用这些对比大麦基因型，对生物量、水分关系、光合作用和渗透调节的影响进行了比较分析，以验证筛选的可靠性并获取可信的性状作为大麦耐旱性筛选的指标。正如预期，所选耐旱基因型在水分缺乏条件下比耐旱性敏感的基因型表现出更少的株高生物量减少，这与大规模筛选的结果显著正相关，证实了本研究中两种干旱条件下耐旱性筛选的可靠性。同样，在水分缺乏胁迫下，对比基因型的水分关系、光合活性和渗透调节性状存在显著差异，并且它们与大麦幼苗的生长高度相关，表明它们有潜力成为耐旱性选择的指标。对这些性状在耐旱性中的变量重要性分析表明，汁液渗透摩尔浓度和最年轻的全展叶相对含水量是筛选幼苗期大麦耐旱性的适宜指标。