title: Alleviating versus stimulating effects of bicarbonate on the growth of Vallisneria natans under ammonia stress.
abstract: Bicarbonate plays a crucial role in limiting the growth of submersed aquatic macrophytes in eutrophic lakes, and high ammonia is often toxic to macrophytes. In order to evaluate the combined effect of HCO3 (-) and total ammonia (i.e., the total of NH3 and NH4 (+)) on submersed macrophytes Vallisneria natans, the growth and physiological response of V. natans in the presence of HCO3 (-) and ammonia were studied. The results showed that with the increase of ammonia, morphological parameters of V. natans declined. In contrast, increased HCO3 (-) concentration stimulated the growth of V. natans, especially when the NH4 (+)-N/NO3 (-)-N ratio was 1:7. High ammonia concentration induced excess free amino acids (FAA) accumulation and soluble carbohydrates (SC) depletion in plant tissues. However, the elevated HCO3 (-) promoted the synthesis of SC and rendered the decrease of FAA/SC ratio. The results also suggested that HCO3 (-) could partially alleviate the stress of ammonia, as evidenced by the decrease of FAA/SC ratio and the growth enhancement of V. natans when the ammonia concentration was 0.58 mg L(-1). Given the fact that HCO3 (-) is probably the dominant available carbon source in most eutrophic lakes, the ability of V. natans to use HCO3 (-) for SC synthesis may explain the alleviating effect of HCO3 (-) on V. natans under ammonia stress.
authors: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210046, China.
authors: Yanyan
authors: Y
authors: Dou
authors: Baozhong
authors: B
authors: Wang
authors: Liangyan
authors: L
authors: Chen
authors: Daqiang
authors: D
authors: Yin
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000641:Ammonia / Q000008:administration & dosage* / Q000633:toxicity; D001639:Bicarbonates / Q000008:administration & dosage*; D050260:Carbohydrate Metabolism / Q000187:drug effects; D031321:Hydrocharitaceae / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001639:Bicarbonates; D000641:Ammonia
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