Volume 13, Issue 5 (2011)
JAST 2011, 13(5): 687-699 |
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Deng C, Zhang G, Pan X. Photosynthetic Responses in Reed (Phragmites australis (CAV.) TRIN. ex Steud.) Seedlings Induced by Different Salinity-Alkalinity and Nitrogen levels. JAST 2011; 13 (5) :687-699
URL: http://jast.modares.ac.ir/article-23-1590-en.html
URL: http://jast.modares.ac.ir/article-23-1590-en.html
1- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin, 130012, People Republic of China.
2- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011, People Republic of China.
2- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011, People Republic of China.
Abstract: (6470 Views)
Many Phragmites-dominated wetlands have been markedly salinized and alkalinized in the Songnen Plain, northeastern China. Agricultural wastewater with high nitrogen content has been discharged into these alkalinized-salinized wetlands. To understand the effect of salinity-alkalinity on reed (Phragmites australis) seedlings at various nitrogen levels, we examined photosynthesis rate, chlorophyll fluorescence characteristics, and chlorophyll content of reed seedlings using gas exchange and chlorophyll a fluorescence tests. The greatest decreases (by 82%, 15%, 82% and 98%) of net photosynthesis rate (Pn), maximal efficiency of photosystem II (PSII) photochemistry (FV/FM), comprehensive photosynthesis performance index (PIABS) and plant height growth rate were observed at high salinity-alkalinity (mixed with 150 mM NaCl and 100 mM NaHCO3). Stomatal limitation was the main reason for decreased photosynthesis rate at low salinity-alkalinity (mixed with 50 mM NaCl and 25 mM NaHCO3). The activity of PSII was significantly inhibited at high salinity-alkalinity. Both donor and acceptor sides of PSII are the target sites of high salinity-alkalinity. High N (30 mM) at low salinity-alkalinity and moderate N (15 mM) at high salinity-alkalinity mitigated the toxicity of salinity-alkalinity on reeds and promoted plant height growth, chlorophyll synthesis, and PSII activity. Proper levels of N partly reduced the toxicity of salinity-alkalinity on the donor and acceptor sides of PSII. This suggests that agricultural wastewater containing high level of nitrogen may be helpful in restoration of Phragmites-dominated salinized wetland, though the N level needed for salinity-alkalinity stressed reed varies with the salinity-alkalinity level.
Keywords: Chlorophyll fluorescence, Nitrogen, Gas exchange, Alkalinized-salinized wetlands, Phragmites australis
Received: 2010/01/19 | Accepted: 2010/06/29 | Published: 2011/04/21
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