Corrections for rooting volume and plant size reveal negative effects of neighbour presence on root allocation in pea

Plants are able to detect the presence of their neighbours belowground. The associated root responses may affect plant performance, plant-plant interactions and community dynamics, but the extent and direction of these responses is heavily debated. Some studies suggest that plants will over-proliferate roots in response to neighbours at the expense of reproduction, which was framed as a “tragedy of the commons”. Others proposed an “ideal free distribution” hypothesis, stating that plants produce roots simply as a function of the amount of available nutrients. However, experimental evidence for either hypothesis that is unbiased by confounding effects of rooting volume and plant size in their experimental setups is still lacking. We grew split-root pea plants in the presence or absence of a belowground neighbour at a range of rooting volumes, while providing equal amounts of nutrients per plant. Path analyses were used to disentangle the direct effects of neighbour presence on allocation...植物能够感知地下邻近植株的存在。由此引发的根系响应可能会影响植株生长表现、种间相互作用与群落动态，但此类响应的程度与方向至今仍存在广泛争议。部分研究表明，植物在感知到邻近植株时会过度增生根系，却以牺牲繁殖能力为代价，这一现象被归纳为"公地悲剧（tragedy of the commons）"。另有研究者提出"理想自由分布（ideal free distribution）"假说，认为植物根系的生长仅取决于有效养分的含量。然而，目前尚未有能够排除实验设计中根系容积与植株体量混淆效应的无偏实验证据，可为这两种假说提供支撑。本研究通过设置梯度根系容积，在有、无地下邻近植株的条件下培养分根豌豆植株（split-root pea plants），并为每株植物提供等量养分。本研究采用路径分析（path analysis）厘清邻近植株存在与否对养分分配的直接影响……