Influence of salt stress on propagation, growth and nutrient uptake of typical aquatic plant species

Anthropogenic activities and natural causes contribute to the increase of the area and degree of degraded saline wetlands in arid/semi‐arid and coastal regions. The objective of this study was to determine the salt tolerance of seven aquatic plant species during asexual reproduction and at continued growth stage. The species were exposed to five salinity treatments from 0.3 (control) to 20 dS/m during the 30 day experiment. Data were collected on asexual reproduction and growth, chlorophyll content index in leaves, Na+ and K+ concentrations and total nitrogen (TN) and total phosphorus (TP) concentrations in above‐ground biomass (AGB) and below‐ground biomass (BGB). The results of this study showed that: 1) the increase of salinity (especially at a salinity level of EC≥15 dS/m) generally inhibited the capacity for asexual reproduction and reduced the chlorophyll content index in leaves; 2) total dry biomass of plants was significantly and negatively related to asexual reproduction of plants; 3) species‐specific salt tolerance mechanisms were shown as indicated by the Na+ and K+ concentrations and Na+/K+ ratios in different parts of plants; and 4) the absorption of TN and TP were inhibited at high salinity level (i.e., EC=20 dS/m) in AGB and BGB of most tested plant species. Salinity may enhance plant uptake of TN and TP under certain condition (e.g., EC at 5, 10 and 15 dS/m). In general, giant reed (Arundo donax) and alligator weed (Alternanthera philoxeroides) showed better asexual reproduction and growth capacity under high salt stress, and they should be considered as potential plant species to be used in the restoration of degraded saline wetlands and/or in treatment wetlands for decontaminating saline wastewater.