Growth and Rooting Depth Characteristics of Hydrilla Verticillata (L.f.) Royle and Myriophyllum Spicatum L. on Fertilized and Unfertilized Sediments.

摘要

In a series of controlled greenhouse experiments, growth and rooting depth characteristics of Hydrilla verticillata (L.f.) Royle and Myriophyllum spicatum L. were examined relative to sediment-N availability, over a range of sediment depths from 10 to 60 cm. Each species was grown separately on fine-textured, inorganic sediment, either amended with ammonium chloride (N-amended) or rendered N-poor due to previous support of submersed macrophyte growth (nonamended). For both species, diminished biomass production was accompanied by increased root-to-shoot ratios and increased rooting depth (to 60 cm) on nonamended sediment. High production levels in Myriophyllum and Hydrilla on N-amended sediment were unaffected by sediment depth, indicating (along with high tissue N concentrations) that the availability of N under those conditions was nonlimiting. With increased depth of nonamended sediment, both Hydrilla and Myriophyllum increased production and mitigated N-deficiency m plant tissues by increasing root accession of this nutrient from greater sediment depths. This ability, speculated here to be more or less developed in other macrophyte species, may affect the outcome of interspecific interactions, particularly when N concentrations in sediment are low. Aquatic plants, Nitrogen, Sediment composition, Hydrilla, Nutrient limitation, Sediment nutrient availability, Myriophyllum, Nutrient uptake, Submersed macrophytes.