%0 Journal Article
%A CHAI Min-Wei
%A LI Rong-Yu
%A QIU Guo-Yu
%A SHEN Xiao-Xue
%T Effects of Ammonium Nitrogen on Physiological and Ecological Characteristics of <i>Kandelia obovata</i> under Cadmium Stress
%D 2018
%R 10.7525/j.issn.1673-5102.2018.05.003
%J Bulletin of Botanical Research
%P 653-660
%V 38
%N 5
%X The heavy metal pollution and excess input of nutrient elements become two important environmental problems in mangrove forest. The ecological risk of cadmium(Cd) is relatively high, and ammonium nitrogen(NH<sub>4</sub><sup>+</sup>-N) is the main speciation of nitrogen in sediment of mangrove. In order to clarify the growth and physiological characteristics of <i>Kandelia obovata</i> under combined stresses of Cd and NH<sub>4</sub><sup>+</sup>-N, pot experiments were conducted. Plant growth, leaf photosynthetic parameters(photosynthetic rate(<i>P</i><sub>n</sub>), stomatal conductance(<i>G</i><sub>s</sub>), intercellular CO<sub>2</sub> concentration(<i>C</i><sub>i</sub>) and transpiration rate(<i>E</i>)), leaf malondialdehyde(MDA), leaf soluble sugar, and root activity were determined. The results showed that:(1)Plant growth and leaf transpiration rate(<i>E</i>) of <i>K.obovata</i> decreased under single Cd stress, with root activity to be reduced under higher single Cd stress; (2)Under Cd stress, low concentration of NH<sub>4</sub><sup>+</sup>-N significantly improved growth of root, but did not significantly improved growth of aboveground part, and leaf photosynthesis(<i>P</i><sub>n</sub>, <i>G</i><sub>s</sub> and <i>E</i>); while high concentration of NH<sub>4</sub><sup>+</sup>-N significantly reduced plant growth, and leaf photosynthesis(<i>P</i><sub>n</sub>, <i>G</i><sub>s</sub> and <i>E</i>); (3)Under Cd1 treatment, root activity first increased and then decreased with increasing NH<sub>4</sub><sup>+</sup>-N concentration; while reduced root activity were shown under Cd2 and Cd3 treatments with NH<sub>4</sub><sup>+</sup>-N supply; (4)Under Cd stress, low concentration of NH<sub>4</sub><sup>+</sup>-N did not significantly reduce content of malondialdehyde(indicative of oxidative damage) and soluble sugar(indicating osmotic adjustment), while high concentration of NH<sub>4</sub><sup>+</sup>-N significantly reduced the content of MDA and soluble sugar. Therefore, the lower concentration of NH<sub>4</sub><sup>+</sup>-N can alleviate the Cd toxicity to root, with limited emission on aboveground part; while high concentration of NH<sub>4</sub><sup>+</sup>-N and Cd combined stress would have a synergistic effect to aggravate Cd toxicity to <i>K.obovata</i>.
%U https://bbr.nefu.edu.cn/EN/10.7525/j.issn.1673-5102.2018.05.003