The growth rate hypothesis (GRH) states that a negative correlation exists between the growth rate and N:P and C:P ratios, because fast-growing organisms need relatively more phosphorus-rich RNA to support their high rates of protein synthesis. However, it is still uncertain whether the GRH is applicable in freshwater wetlands. Several studies have shown that water level and sediment type are key factors influencing plant growth and plant C:N:P characteristics in freshwater wetlands. Thus, this study aimed to elucidate the influence of these factors on plant growth and test the GRH under varying water levels and sediment conditions. We designed a controlled experiment at three water levels and under three sediment types using the two dominant plants (Carex brevicuspis and Polygonum hydropiper) in the East Dongting Lake wetland, and we further investigated the relative growth rate (RGR); concentrations of total carbon (TC), total nitrogen (TN), and total phosphorus (TP); and plant stoichiometry (ratios of C:N, C:P, and N:P) in the aboveground and belowground parts and whole plants in both species. Results demonstrated that the RGR and TC of both species decreased significantly with decreasing sediment nutrient supply and increasing water level. However, TN and TP of both species were markedly higher at high water levels than at low water levels; furthermore, these were significantly higher on clay than on the other two sediment types at each water level. The C:N and C:P ratios of both species decreased with increasing sediment nutrient supply and water level, whereas N:P decreased in both species with increasing sediment nutrient supply. The aboveground part of C. brevicuspis as well as the aboveground part and whole plant of P. hydropiper were negatively correlated with N:P, which is consistent with the GRH. However, the relationship between the belowground RGR and N:P of these species was inconsistent with GRH. Therefore, the water level and sediment type and their interaction significantly influenced plant RGR and C:N:P characteristics. The RGR and plant stoichiometry differed significantly between plant organs, indicating that the GRH needs refinement when applied to wetland macrophytes.

增长率假设（GRH）指出，增长率与N：P和C：P比率之间存在负相关关系，因为快速生长的生物需要相对更多的富磷RNA来支持其高蛋白质合成率。但是，仍然不确定GRH是否适用于淡水湿地。多项研究表明，水位和沉积物类型是影响淡水湿地植物生长和植物C：N：P特性的关键因素。因此，本研究旨在阐明这些因素对植物生长的影响，并在变化的水位和沉积条件下测试GRH。我们使用两种优势植物设计了在三种水位和三种沉积物类型下的对照实验（短草苔藓 和 水）在东洞庭湖湿地，我们进一步调查了相对增长率（RGR）；总碳（TC），总氮（TN）和总磷（TP）的浓度；地上和地下部分以及整个物种的植物的化学计量（C：N，C：P和N：P的比率）。结果表明，随着沉积物养分供应的减少和水位的增加，两种物种的RGR和TC均显着下降。但是，在高水位时，两个物种的总氮和总磷显着高于低水位。此外，在每种水位下，粘土上的这些显着高于其他两种沉积物类型。两种物种的C：N和C：P比随沉积物养分供应和水位的增加而降低，而N：随着沉积物养分供应的增加，两种物种的磷均降低。地上部分短小隐孢子虫 以及地上部分和整个植物 水hydro与N：P呈负相关，这与GRH一致。但是，这些物种的地下RGR和N：P之间的关系与GRH不一致。因此，水位和沉积物类型及其相互作用显着影响植物的RGR和C：N：P特性。植物器官之间的RGR和植物化学计量存在显着差异，表明将GRH应用于湿地大型植物时需要完善。