洪水诱导产生的水生不定根的益处取决于淹没持续时间：将植物表现与根系功能联系起来。
Benefits of flooding-induced aquatic adventitious roots depend on the duration of submergence: linking plant performance to root functioning.
作者信息
Zhang Qian, Huber Heidrun, Beljaars Simone J M, Birnbaum Diana, de Best Sander, de Kroon Hans, Visser Eric J W
机构信息
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525?AJ Nijmegen, the Netherlands.
出版信息
Ann Bot. 2017 Jul 1;120(1):171-180. doi: 10.1093/aob/mcx049.
BACKGROUND AND AIMS
Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious roots (aquatic roots) are commonly formed in flooding-tolerant plant species and are generally assumed to be beneficial for plant growth by supporting water and nutrient uptake during partial flooding. However, the actual contribution of these roots to plant performance under flooding has hardly been quantified. As the investment into aquatic root development in terms of carbohydrates may be costly, these costs may - depending on the specific environmental conditions - offset the beneficial effects of aquatic roots. This study tested the hypothesis that the balance between potential costs and benefits depends on the duration of flooding, as the benefits are expected to outweigh the costs in long-term but not in short-term flooding.
METHODS
The contribution of aquatic roots to plant performance was tested in Solanum dulcamara during 1-4 weeks of partial submergence and by experimentally manipulating root production. Nutrient uptake by aquatic roots, transpiration and photosynthesis were measured in plants differing in aquatic root development to assess the specific function of these roots.
KEY RESULTS
As predicted, flooded plants benefited from the presence of aquatic roots. The results showed that this was probably due to the contribution of roots to resource uptake. However, these beneficial effects were only present in long-term but not in short-term flooding. This relationship could be explained by the correlation between nutrient uptake and the flooding duration-dependent size of the aquatic root system.
CONCLUSIONS
The results indicate that aquatic root formation is likely to be selected for in habitats characterized by long-term flooding. This study also revealed only limited costs associated with adventitious root formation, which may explain the maintenance of the ability to produce aquatic roots in habitats characterized by very rare or short flooding events.
背景与目的
季节性洪水是陆生植物常见的环境胁迫。水生不定根（水生根）通常在耐淹植物物种中形成，一般认为通过在部分淹水期间支持水分和养分吸收，对植物生长有益。然而，这些根在淹水条件下对植物性能的实际贡献几乎未被量化。由于在碳水化合物方面对水生根发育的投入可能成本高昂，这些成本可能会根据特定环境条件抵消水生根的有益影响。本研究检验了以下假设：潜在成本与收益之间的平衡取决于淹水持续时间，因为预计长期淹水时收益大于成本，而短期淹水则不然。
方法
在部分淹没1 - 4周期间，通过实验控制水生根的产生，测试了水生根对龙葵植物性能的贡献。测量了不同水生根发育程度的植物中水生根的养分吸收、蒸腾作用和光合作用，以评估这些根的特定功能。
主要结果
正如预测的那样，淹水植物受益于水生根的存在。结果表明，这可能是由于根对资源吸收的贡献。然而，这些有益效果仅在长期淹水时出现，短期淹水时则没有。这种关系可以通过养分吸收与淹水持续时间依赖的水生根系统大小之间的相关性来解释。
结论
结果表明，在以长期淹水为特征的生境中，水生根的形成可能会被选择。本研究还揭示了与不定根形成相关的成本有限，这可能解释了在以非常罕见或短期淹水事件为特征的生境中，产生水生根的能力得以维持的原因。
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