Water movement induced variations in growth regulation and metabolism of freshwater macrophyte Vallisneria spiralis L. in early growth stages

摘要

Exposure to water movement has been observed to alter various processes in plants. This study attempts to discuss consequences of water movement induced stress on young Vallisneria spiralis plants, since young plants are more vulnerable to damage and their survival is a key factor in successful colonization. Water movement was generated using oscillating grid setups at three different frequencies (1, 2, and 4 Hz). A no-turbulence condition was used as the control. Variations in growth and the alterations in indole acetic acid (IAA), H2O2, peroxidase activity (POD), and carbon metabolism of the plants were measured. Growth of young V. spiralis plants suppressed when exposed to higher turbulences. IAA concentration decreased with increasing turbulence, while H2O2 concentration increased. POD increased in response to the increase in H2O2. The increase in soluble carbohydrates may compensate for the increasing energy demand for respiration under stress. There were evidences for damage to photosynthetic machinery hence reducing carbon assimilation and degrading non-structural carbohydrate storages. Observed variations in the growth, growth regulation and metabolism show that mechanical stress due to turbulence induces significant alterations in plant physiology. Plant stress responses varied with the degree of turbulence they have been exposed.