Effects of Increased Carbon Supply on the Growth, Nitrogen Metabolism and Photosynthesis of Vallisneria natans Grown at
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WETLANDS AND CLIMATE CHANGE
Effects of Increased Carbon Supply on the Growth, Nitrogen Metabolism and Photosynthesis of Vallisneria natans Grown at Different Temperatures Heng Jiang 1,2 & Bing Huang 1,3 & Zhan Qian 1,3 & Yue Xu 1,3 & Xiaohong Liao 1,3 & Ping Song 1,3 & Xichun Li 1,3 Received: 30 January 2020 / Accepted: 25 March 2020 # Society of Wetland Scientists 2020
Abstract Vallisneria natans is often used for the ecological restoration of aquatic vegetation. V. natans thalli were cultured under ambient (400 ppm) and increased carbon supply, with low (18 °C) and high temperature (25 °C). The thalli were used to examine the effects of increased carbon and high temperature on the growth, nitrogen metabolism and photosynthetic characteristics of this plant. At 18 °C, the relative growth rate (RGR), N uptake rate and nitrate reductase (NR) activity of V. natans thalli grown under ambient carbon supply were lower than those under increased carbon supply. The increased carbon supply decreased the RGR, N uptake rate, NR activity and maximum inorganic carbon (Ci) -saturated photosynthetic rate (Vmax) of V. natans when it was cultured at 25 °C. Regardless of the carbon supply levels, the growth, nitrogen uptake capacity and photosynthesis of V. natans thalli grown at 25 °C decreased compared with those of V. natans thalli grown at 18 °C. The RGR and photosynthetic rate of V. natans grown in the presence of increased carbon supply and high temperature were the lowest amongst the four different conditions. Therefore, the negative effects caused by a high temperature were pronounced under the condition of a global atmospheric CO2 increase. Keywords Carbon supply . Temperature . Vallisneria natans . Growth . Photosynthesis . Nitrogen metabolism
Introduction Before the industrial revolution, atmospheric CO2 concentration was basically maintained at 280 ppm. Since the industrial revolution, the atmospheric CO2 concentration has continued to grow rapidly because of forest vegetation destruction and excessive fossil fuel combustion. Since 2004, the World Meteorological Organisation (WMO) has issued a
* Heng Jiang [email protected] * Bing Huang [email protected] 1
Dongting Lake Research Center, Hunan Hydro & Power Design Institute, Changsha 410007, China
2
College of Environment and Energy, South China University of Technology, Guangzhou 510006, China
3
Hunan Key Laboratory of Water Environment Treatment and Ecological Restoration in Dongting Lake, Changsha 410007, China
“Greenhouse Gas Bulletin,” focusing on the concentration of greenhouse gases in Earth’s atmosphere. The CO2 concentration in the atmosphere has increased from 280 ppm in preindustrial times to 404 ppm at present (www.CO2Now.org). The current trend of atmospheric CO2 concentration implies that this concentration may reach or exceed 1000 ppm by 2100 (Fabry et al. 2008). Most researchers agree that CO2 is the most important greenhouse gas that causes global warming. Greenhouse effect likely causes climate warming, a rise in sea levels and a huge impact o
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