Growth And Rooting Depth Characteristics Of Hydrilla Verticillata Lf Royle And Myriophyllum Spicatum L On Fertilized And Unfertilized Sediments PDF Download

This study examines the growth of Hydrilla verticillata (L.f) Royle and Potamogeton americanus C. and S. on both nitrogen-poor and nitrogen-rich sediments and assesses the nature and degree of interspecific interactions between the two species. Extensive greenhouse experiments conducted from May through July 1989 employed sediments differing initially only in sediment nitrogen (fertilized containers: 0.21 + or - 0.01 mg exchangeable N per gram dry sediment; unfertilized containers: 0.01 + or -0.00 mg exchangeable N per gram dry sediment). Species were grown monotypically, as well as in 50:50 mixtures, on each sediment type. Although shoot production did not differ between species in monoculture, shoot production in Hydrilla was diminished by 60 to 76 percent in the presence of Potamogeton. Likewise, canopy development for Hydrilla was reduced in mixtures compared to monocultures, but Potamogeton did not show a similar reduction in canopy. High sediment nitrogen increased canopy development by 50 percent in both species. Above-ground biomass for monotypically grown species was similarly low on unfertilized sediment (6 to 8 g per container). However, on fertilized sediment, aboveground biomass in Potamogeton (approaching 25 g per container) was significantly greater than in Hydrilla (approximately 15 g per container). Aquatic plants, Macrophyte, Biomass, Nitrogen, Density, Production, Interspecific interaction, Sediment.