The Effects of Water Depth on the Growth of Two Emergent Plants in an In-Situ Experiment

Abstract

With the degradation of the global lake ecosystem, aquatic plants are more and more widely used in lake ecological restoration. The effects of water depths on the growth and photosynthetic fluorescence characteristics of two emergent plants (Typha orientalis and Zizania caduciflora) were studied in eutrophic Lake Gehu by in-situ experiments. The results showed that water depth had no significant effect on germination of emergent plants. The water depth changed the morphological characteristics of emergent plants. Plant height, tiller number, leaf length, leaf width, the number of leaf, and the root-shoot ratio decreased with increasing water depth, whereas the number of dead leaves increased with increasing water depth. The biomass of emergent plants was highest when water depth was 40 cm. Water depth had a significant effect on the photosynthetic fluorescence of the emergent plant. Fv/Fm tended to decrease first and then increase with increasing water depth. When the water depth was 20 cm, the ETRmax of emergent plants was significantly higher than that of plants at the other water depths. These results show the suitable water depth range for T. orientalis and Z. caduciflora is 20–60 cm. A deeper water depth for a long time is not conducive to the growth of emergent plants.