The growth and reproduction of plants are highly size-dependent and markedly affected by light intensity. Vallisneria spinulosa S.Z.Yan is a common submersed macrophyte and is widely used in current lake restoration projects. The size of plants to be used to get optimal restoration results is not known, however, and may vary with water clarity. In this study, the effects of different plant sizes (large, medium and small, i.e. approximately 2.40 g, 1.01 g and 0.27 g per plant) on the growth and reproduction of V. spinulosa were tested under three light intensities (high, medium, low, i.e. 25%, 6% and 1% of full sunlight, respectively). Both plant size and light intensity were found to be of great significance for plant growth and reproduction. The relative growth rate (RGR) of biomass was higher for small than for large plants at both high and low light, while the absolute growth rate (AGR) of biomass was higher for large-sized plants at medium and high light intensity. Asexual reproduction of V. spinulosa was positively correlated with plant size and more affected by plant size than by light intensity, while sexual reproduction was most affected by light intensity. RGR and AGR of plant height were highest for medium-sized plants at moderate light intensity. Therefore, the size of submersed macrophytes should be considered when using this species in connection with lake restoration. Verification of our results under field conditions is needed, though, before firm conclusions can be reached about the optimal plant size of V. spinulosa to be used in lake restoration as also other factors like, e.g. periphyton shading and wave actions may play a role.

中文翻译：

---

不同光照强度下植物大小对沉水植物 Vallisneria spinulosa SZYan 生长的影响：对湖泊修复的影响

植物的生长和繁殖高度依赖于大小，并受光照强度的显着影响。Vallisneria spinulosa SZYan 是一种常见的沉水植物，在目前的湖泊修复工程中得到广泛应用。然而，用于获得最佳恢复结果的植物大小尚不清楚，并且可能会随着水的清澈度而变化。在本研究中，在三种光照强度（高、中、低，即分别为全日照的 25%、6% 和 1%）。发现植物大小和光照强度对植物生长和繁殖具有重要意义。在高光和低光下，小型植物的生物量相对增长率（RGR）高于大型植物，而在中等和高光强度下，大型植物的生物量绝对增长率（AGR）更高。V. spinulosa的无性繁殖与植株大小呈正相关，受植株大小的影响大于光照强度，而有性繁殖受光照强度的影响最大。在中等光照强度下，中型植物的株高 RGR 和 AGR 最高。因此，在使用该物种进行湖泊修复时，应考虑沉水植物的大小。然而，在得出关于 V 的最佳植物大小的确切结论之前，需要在田间条件下验证我们的结果。