Influence of flow turbulence on growth and indole acetic acid and H2O2 metabolism of three aquatic macrophyte species

This study aimed to determine the influence of different turbulence levels on morphologically different aquatic macrophyte species. The variations of growth and the alterations of indole acetic acid (IAA) and H2O2 metabolism of three morphologically distinct aquatic macrophyte species, Elodea nuttallii, Potamogeton crispus and Vallisneria spiralis were studied in the exposure to three different turbulence conditions. Plants were subjected to turbulence generated by vertically oscillating horizontal grids at three different frequencies: 1, 2 and 4 Hz. A no-turbulence condition was used as a control. The growth of V. spiralis and E. nuttallii was suppressed by exposure to greater turbulence, though increased turbulence enhanced the growth of P. crispus. The growth rate of plants was positively correlated with IAA concentration. IAA concentration was negatively correlated with turbulence level in V. spiralis and E. nuttallii, while it was positively correlated in P. crispus. H2O2 concentration was positively correlated with turbulence level in the former species, while it had no correlation in the latter. P. crispus showed more resistance to turbulence-induced mechanical stress and growth suppression than the other two species. The observed variations of growth and IAA and H2O2 metabolism showed that plant morphology has a significant influence on the response to flow turbulence. The results from this study provide a basis for understanding the mechanism and consequential morphological changes in plants that grow in moving water.