Data for: Shoot and root growth in response to hydrological fluctuations in the drought-tolerant Knautia arvensis and wet-tolerant Lythrum salicaria

This dataset represents a greenhouse experiment investigating the effects of fluctuating soil hydrology on plant growth and flowering, including root diameter and root length in raingardens. Plants in raingardens are important for evapotranspiration and maintaining infiltration properties. However, hydrological conditions, including cycles of dry and saturated conditions, influence plant performance and therefore affect plant selection. This study includes an experiment to assess whether fluctuating hydrology impacts growth, flowering, and root morphology in two species: the drought-tolerant Knautia arvensis and the wet-tolerant Lythrum salicaria. The results show that Knautia reduced growth under flooding cycles, while Lythrum reduced growth and flowering under drought cycles. Repeated consecutive drought and flooding cycles negatively influenced the growth of both species in the same way, with flooding affecting Knautia and drought affecting Lythrum. Lythrum showed more plasticity than Knautia, allocating more biomass to roots during drought cycles. Flooding cycles reduced root length in Knautia, while the drought cycles and consecutive Drought+Flooding cycles increased root diameter and decreased root length in Lythrum. Both species had coarse roots (> 2 mm) to support infiltration through biopores. If we assume that raingardens have free drainage and only rarely flood, drought-tolerant traits are more important. However, wet-tolerant species can benefit the system, especially through higher water use.

本数据集对应一项温室实验，旨在探究土壤水文动态波动对雨水花园（raingardens）中植物生长与开花的影响，实验同时测定了植物的根系直径与根长。雨水花园中的植物对于蒸散作用以及维持土壤入渗性能至关重要。然而，包括干湿循环在内的水文条件会影响植物生长表现，进而影响适生植物的筛选。本研究通过实验评估水文动态波动是否会对两种物种的生长、开花及根系形态产生影响：耐旱的山萝卜（Knautia arvensis）与耐湿的千屈菜（Lythrum salicaria）。实验结果显示，山萝卜在淹水循环条件下生长受到抑制，而千屈菜在干旱循环条件下的生长与开花均受到阻碍。连续反复的干旱与淹水循环对两种物种的生长均产生负面影响，具体表现为淹水胁迫影响山萝卜，干旱胁迫影响千屈菜。千屈菜相较于山萝卜具有更强的表型可塑性，在干旱循环过程中会将更多生物量分配至根系。淹水循环会缩短山萝卜的根长，而干旱循环以及连续的“干旱-淹水”循环则会增大千屈菜的根系直径并降低其根长。两种植物均拥有粗根系（> 2 mm），可通过生物孔隙辅助土壤入渗过程。若假设雨水花园具备自由排水条件且极少发生淹水，则耐旱性状的植物更为适配；而耐湿物种则可通过更高的水分利用效率为雨水花园系统带来益处。