Table_3_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.

旱灾是一种破坏性极强的环境限制因素，对大麦的农艺生产产生严重影响。为促进育种进程，亟需丰富的种质资源和可靠的评估体系，以便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个栽培大麦基因型和190个野生大麦基因型进行了筛选，以评估其在幼苗阶段的耐旱性，筛选条件包括水分亏缺和聚乙二醇（PEG）模拟的干旱。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，大麦幼苗的耐旱性诱导下降并无显著差异。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，这为识别18个在耐旱性上存在差异的基因型奠定了基础。通过对这些对比基因型在生物量、水分关系、光合作用和渗透调节方面的比较分析，旨在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标准。正如预期，所选耐旱基因型在水分亏缺条件下与耐旱性敏感基因型相比，其枝条生物量的减少幅度明显较小，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，在水分亏缺胁迫下，对比基因型在水分关系、光合活性和渗透调节方面的性状存在显著差异，且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重要性分析表明，幼嫩完全展开叶片的汁液渗透压和相对含水量是大麦幼苗阶段耐旱性筛选的适宜指标。