| Research Articles |
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| Effects of sodium on nitrate uptake and osmotic adjustment of Suaeda physophora |
| JunFeng YUAN, ChangYan TIAN, Gu FENG |
| 1 Key Laboratory of Oasis Ecology and Desert Environment, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; 2 College of Resource and Environmental Science, China Agricultural University, Beijing 100094, China |
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Abstract Na+ ions play an important role in the growth of halophyte. The effect of Na+ ions on nitrate uptake and osmotic adjustment in the euhalophyte Suaeda physophora was investigated under glasshouse conditions. Seedlings were exposed to 1 mmol/L NaCl (control), 300 mmol/L NaCl, 150 mmol/L NaCl plus 150 mmol/L KCl or 300 mmol/L KCl treatments for 24 d. Dry weight was not affected greatly by different salt treatments, but water content and succulence in leaves of S. physophora were significantly increased at 300 mmol/L NaCl and 150 mmol/L NaCl plus 150 mmol/L KCl treatments. The concentrations of Na+ and NO3- in leaves of S. physophora were the highest at 150 mmol/L NaCl plus 150 mmol/L KCl, but lowest at 300 mmol/L KCl treatment. Moreover, the increase of NO3- concentration did not result in the decrease of Cl- concentration at 150 mmol/L NaCl plus 150 mmol/L KCl treatments. The estimated contribution of NO3- to osmotic potential (CNO3) in leaves of S. physophora was 9.8% at 150 mmol/L NaCl plus 150 mmol/L KCl, and CNa and CCl were 31.0% and 23.3%, respectively. However, CNO3, CNa and CCl were respectively 1.6%, 7.9% and 11.9% at 300 mmol/L KCl treatment. It is concluded that Na+ stimulates NO3- absorption and the stimulation is independent on the internal or the external Cl- concentration in the euhalophyte S. physophora. These characteristics may explain the high levels of N in leaves of saline desert plants in arid ecosystem.
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Received: 03 May 2010
Published: 07 September 2010
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