Abstract Regenerating oak seedlings by different methods impacts taproot architecture, root-to-shoot allometry and, potentially, soil water use and plant growth under water limitations. In the present study, Quercus robur (L.) seedlings regenerated by four different methods – sowing (acorn-sown seedlings), sowing followed by shoot clipping (coppiced), sowing followed by root-pruning (root-pruned), and container planting with the root plug intact (containerized) – were subjected to four water-shortage regimes – full watering and 75, 50, and 25% of full watering. These treatments were used to test the hypotheses that root morphology, anatomy and biochemistry varied among regeneration methods, and, thus, differentially affected plant responses to water-shortages. For most traits, the response to water shortage of acorn-sown and containerized seedlings was similar, and opposite to that of coppiced and root-pruned seedlings. Water shortage did not change tree allocation to total root biomass among regeneration methods but altered the partitioning between absorptive and structural roots within the root system. Acorn-sown and containerized seedlings produced more pioneer roots, and coppiced and root–pruned seedlings more highly-branched fine roots with greater specific root length and specific root surface area under greater water shortage. Thus, acorn-sown and containerized oaks appeared to be primed for water foraging, and coppiced and root-pruned oaks for water absorption efficiency in response to water shortage. Water shortage caused a reduction in nonstructural carbohydrate concentrations in fine roots of acorn-sown and containerized seedlings and in the taproot of coppiced and root-pruned seedlings. Results generally indicated that seedling response to water limitation depended on the regeneration method, highlighting the importance of root–to–shoot allometry, taproot development, and carbon reserve mobilization for plant functioning under water shortage. Acorn-sown and containerized oaks seedlings might be more suitable for forest regeneration in sites characterized by severe water shortage periods. The reduction of taproot starch reserves under strong water shortage may render root-pruned oak trees more susceptible to topsoil water deficit than acorn-sown trees. This work contributes to understand drought acclimation and to identify the most adequate forestry regeneration practices to adapt forest ecosystems to ongoing climatic changes.

中文翻译：

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幼苗再生技术影响根系和栎树幼苗对缺水的反应

摘要 通过不同方法再​​生橡树幼苗会影响主根结构、根到芽异速生长，并可能影响水分限制下的土壤水分利用和植物生长。在本研究中，Quercus robur (L.) 幼苗通过四种不同的方法再生——播种（橡子播种的幼苗）、播种后剪枝（coppiced）、播种后剪根（root-pruned）和容器种植在根栓完好（容器化）的情况下——经历了四种缺水状况——充分浇水和 75%、50% 和 25% 的充分浇水。这些处理被用来测试根的形态、解剖结构和生物化学在再生方法中不同的假设，因此，不同地影响植物对缺水的反应。对于大多数特征，橡子播种和容器化幼苗对缺水的反应相似，但与短茬和剪根幼苗的反应相反。缺水并没有改变再生方法中树木对总根生物量的分配，而是改变了根系内吸收性根和结构性根之间的分配。橡子播种和容器化幼苗在更大的缺水情况下产生更多的先锋根，而短茬和修剪的幼苗产生更多高分枝的细根，具有更大的比根长度和比根表面积。因此，橡树播种和容器化橡树似乎适合进行水觅食，而矮化和修剪根部的橡树则是为了应对缺水的吸水效率。缺水导致橡子播种和容器化幼苗的细根中以及修剪和修剪根部幼苗的主根中的非结构性碳水化合物浓度降低。结果普遍表明，幼苗对水分限制的反应取决于再生方法，突出了根到芽异速生长、主根发育和碳储备动员对缺水条件下植物功能的重要性。在严重缺水时期，橡子播种和集装箱橡树幼苗可能更适合森林再生。在严重缺水的情况下，主根淀粉储备的减少可能会使根修剪的橡树比橡子播种的树更容易受到表土水分不足的影响。