AimsRoot characteristics are important for predicting plant and ecosystem responses to resource scarcity. Simple, categorical traits for roots could be broadly applied to ecosystem function and restoration experiments, but they need to be evaluated for their role and behaviour under various stresses, including water limitation. We hypothesised that more complex root architectures allow more plastic responses to limited water than do tap roots.MethodsWe carried out two greenhouse experiments: one with a range of grassland plant species; the other with only species of Asteraceae to test the responsiveness of root architectural classes to location of limited water in the soil column. Using trait screening techniques and X-ray tomography, we measured the plasticity of the roots in response to water location.ResultsPlasticity of root biomass was lowest in tap rooted species, while fibrous and rhizomatous roots allocated biomass preferentially to where the soil was wettest. X-ray tomography indicated that root morphology was least plastic in rhizomatous species.ConclusionsOur results provide a starting point to effective categorisation of plants in terms of rooting architecture that could aid in understanding drought tolerance of grassland species. They also demonstrate the utility of X-ray tomography in root analyses.

中文翻译：

---

根系结构控制着应对干旱的可塑性

目标根特征对于预测植物和生态系统对资源稀缺的反应非常重要。简单的根系特征可以广泛应用于生态系统功能和恢复实验，但需要评估它们在各种压力（包括水限制）下的作用和行为。我们假设更复杂的根结构比直根能够对有限的水产生更多的塑性反应。方法我们进行了两项温室实验：一项是针对一系列草原植物物种；另一项是针对多种草原植物。另一个仅使用菊科物种来测试根结构类别对土壤柱中有限水的位置的响应。使用性状筛选技术和 X 射线断层扫描，我们测量了根对水位置的可塑性。结果直根物种的根生物量可塑性最低，而须根和根茎根优先将生物量分配到土壤最湿润的地方。X 射线断层扫描表明根茎物种的根形态可塑性最小。结论我们的结果为根据根结构对植物进行有效分类提供了一个起点，这有助于了解草原物种的耐旱性。他们还展示了 X 射线断层扫描在牙根分析中的实用性。