Variation in biomass allocation patterns has been considered a strategy in clonal plants to adapt to various environments. It has been predicted that clonal plants allocate more biomass to spacers (i.e., stolon and rhizomes) at moderate resource levels. We tested the prediction in an aquatic clonal plant Salvinia natans by subjecting it to nine nutrient levels under either a low or a high light condition. Biomass, ramet number and mean stolon internode length were overall greater under the moderate nutrient levels and the high light condition. The responses of plant growth and morphology to nutrient availability were unimodal under the high light condition, but bimodal under the low light condition. Floating frond mass ratio was overall smaller in the high than in the low light condition, but the reverse was true for submerged frond mass ratio and stolon mass ratio. Under the high light condition, floating front mass ratio increased with increasing nutrient availability, and a reverse pattern was found for submerged mass ratio and stolon mass ratio. Under the low light condition, the response of floating mass ratio to nutrient availability was hump shaped, but that of submerged mass ratio and stolon mass ratio was U shaped. Therefore, our findings do not support the theoretical prediction that biomass allocation to spacers is the highest at moderate nutrient availabilities, but suggest that nutrient availability and light intensity can interact to influence growth, morphology and biomass allocation of aquatic clonal plants.

中文翻译：

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没有证据表明在浮游植物中，在中等资源水平下，生物量能更多地分配给茎

生物量分配模式的变化已被认为是克隆植物适应各种环境的一种策略。据预测，克隆植物在中等资源水平下会向间隔区（即茎和根茎）分配更多的生物量。我们在水生无性系Salvinia natans中测试了预测通过在弱光或强光条件下使其达到九种营养水平。在中等营养水平和高光照条件下，生物量，分株数和平均茎节间长度总体较大。在强光条件下植物生长和形态对养分有效性的响应为单峰响应，而在弱光条件下为双峰响应。浮叶质量比在高光下总体上要比弱光条件下小，但是对于浸没叶质量比和茎质量比而言，情况恰恰相反。在强光条件下，浮游前的质量比随养分利用率的增加而增加，而淹没质量比和sto茎质量比则呈现相反的规律。在弱光条件下，漂浮质量比对养分有效性的响应呈驼峰形，浸入质量比和茎质量比为U形。因此，我们的发现不支持在中等养分利用率下将生物量分配给间隔物的理论预测，但是表明养分利用率和光强度可以相互作用来影响水生克隆植物的生长，形态和生物量分配。