Abstract Crop tolerance and avoidance are critical adaptation mechanisms to cope with drought stress but they contribute differently to grain yield formation. Little is known about the different roles of these two mechanisms in long-term crop breeding. A meta-analysis was conducted to determine the different effects of drought tolerance and avoidance mechanisms on the drought adaptation of wheat crops. The meta-analysis summarized the results of 283 published papers in international journals, and illustrated that primitive wheat genotypes, including wild, cultivated diploids, tetraploids and old hexaploids, preferentially showed a drought avoidance strategy, as evidenced by large root biomass, small leaf area, and reduced stomatal conductance under water deficits. Modern hexaploid genotypes showed stronger drought tolerance advantages, such as high leaf water potential and osmotic adjustment, with a small root system. The meta-analysis indicated that the breeding process of dryland wheat has been continuously enhancing drought tolerance while weakening drought avoidance. Under severe water deficits, old hexaploid wheat genotypes with drought avoidance characteristics showed lower reduction of aboveground biomass and yield than modern genotypes with stronger drought tolerance features, while under mild and moderate water deficits genotypes with stronger drought tolerance features had higher yields and aboveground biomass. The meta-analysis provide information for making decisions on the direction of modern crop breeding and the implementing of managing practices to cope with drought stress, which frequency and severity is increasing with the advent of climate change.

中文翻译：

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小麦育种强调耐旱性，而忽略了避免干旱的优势：荟萃分析

摘要 作物耐受和避免是应对干旱胁迫的关键适应机制，但它们对粮食产量形成的贡献不同。关于这两种机制在长期作物育种中的不同作用知之甚少。进行了荟萃分析以确定耐旱和避免机制对小麦作物干旱适应的不同影响。荟萃分析总结了在国际期刊上发表的 283 篇论文的结果，并说明原始小麦基因型，包括野生、栽培二倍体、四倍体和老六倍体，优先表现出避旱策略，如根生物量大，叶面积小。 ，以及在缺水情况下降低气孔导度。现代六倍体基因型表现出更强的耐旱优势，如叶水势高，渗透调节，根系小。荟萃分析表明，旱地小麦的育种过程不断增强抗旱性，同时减弱避旱性。在严重缺水条件下，具有避旱特性的老六倍体小麦基因型的地上生物量和产量下降幅度低于具有较强耐旱特性的现代基因型，而在轻度和中度缺水条件下，具有较强耐旱特性的基因型具有更高的产量和地上生物量。元分析为现代作物育种方向的决策和实施应对干旱压力的管理实践提供信息，随着气候变化的到来，干旱压力的频率和严重程度正在增加。