Carbohydrate concentration and tolerance in three riparian plant species from the Three Gorges Reservoir region exposed to long-term submergence
FakultätenFakultät für Naturwissenschaften
LizenzStandard (Fassung vom 01.10.2008)
The previous seasonal river flooding in the Three Gorges reservoir (TGR) region (Chongqing, China) occurs in summer. After the construction of TGR, high water table will be maintained in winter under low water temperature conditions and a low water table in summer. These contrasting flooding regimes are expected to influence flooding tolerance of the riparian plant species and consequently the vegetation. Salix variegata Franch. (shrub), Arundinella anomala Steud. (grass) and Althernanthera philoxeroides (Mart.) Griseb (clonal herb) can survive of complete submergence for several months. The hypothesis that long-term flooding tolerance is closely associated with maintaining carbohydrate level was tested. S. variegata and A. anomala plants survived 6 months of waterlogging without significant decrease of water soluble carbohydrate concentration compared with non-flooded plants. Complete submergence decreased carbohydrate level significantly, which continued with prolonged duration and finally death occurred after 4 to 6 months of inundation. A further two months of submergence with different water temperature (10°C, 20°C and 30°C) showed that at lower water temperature carbohydrate level was higher in both A. anomala and A. philoxeroides plants. Lower water temperature also resulted in lower survival rate in A. anomala plants and and faster recovery in A. philoxeroides plants. Carbohydrate concentration and survival in the recovery period was very similar in darkness-treated and submerged A. anomala plants. In A. philoxeroides plants, no significant differences of carbohydrate level were found between darkness-treated plants and submerged plants during the submergence period. These studies indicated that flooding tolerance can be partially explained on the basis of carbohydrate metabolism. Death from submergence could be caused by depletion of carbohydrate reserve. Lower water submergence can slow down carbohydrate utilization and increase plant flooding tolerance.
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