Chin J Plant Ecol ›› 2017, Vol. 41 ›› Issue (2): 196-208.DOI: 10.17521/cjpe.2016.0128

• Research Articles • Previous Articles     Next Articles

Effects of nitrogen addition on photosynthetic characteristics of Leymus chinensis in the temperate grassland of Nei Mongol, China

Zhan-Wei ZHAI1, Ji-Rui GONG1,*(), Qin-Pu LUO1, Yan PAN1, Taogetao BAOYIN2, Sha XU1, Min LIU1, Li-Li YANG1   

  1. 1Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, College of Resources Science & Technology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China

    2College of Life Sciences, Inner Mongolia University, Hohhot 010021, China
  • Received:2016-04-07 Accepted:2016-12-25 Online:2017-02-10 Published:2017-03-16
  • Contact: Ji-Rui GONG
  • About author:KANG Jing-yao(1991-), E-mail:


Aims The increased atmospheric nitrogen (N) deposition due to human activity and climate change greatly causes grassland ecosystems shifting from being naturally N-limited to N-eutrophic or N-saturated, and further affecting the growth of grass species. The aims of this study are: 1) to evaluate the effects of different N addition levels on morphology and photosynthetic characteristics of Leymus chinensis; 2) to determine the critical N level to facilitate L. chinensis growth.
Methods We conducted a different N addition levels experiment in dominant species in the temperate steppe of Nei Mongol. The aboveground biomass, morphological and leaf physiological traits, pigment contents, chlorophyll a fluorescence parameters and biochemical parameters of L. chinensis were investigated.
Important findings Our results showed that aboveground biomass first increased and then decreased with the increased N, having the highest values at the 10 g N·m-2·a?1 treatment, but the 25 g N·m-2·a?1 still significantly increased the aboveground biomass relative to 0 g N·m-2·a?1. Leymus chinensis accommodate low N situation through allocating less N to carboxylation system and decreasing leaf mass per area (LMA) in order to get more light energy. Moderate N addition captured more light energy through increasing total chlorophyll (Chl) contents and decreasing the ratio of Chl a/b. Moderate N addition increased LMA, carboxylation efficiency, maximum carboxylation rate (Vcmax), maximum electron transport rate (Jmax) and decreased Jmax/Vcmax, thus allocating more N to carboxylation system to enhance carboxylation capability. Moreover, the photochemical activity of PSII was increased through higher effective quantum yield of PSII photochemistry, electron transport rate and photochemical quenching coefficient. Excessive N addition had negative effects on physiological variables of L. chinensis due to lower carboxylation capability and photochemical activity of PSII, further leading to decreased net photosynthetic rate, whereas increased non-photochemical quenching coefficient and carotenoids played the role in the dissipation of excess excitation energy. Overall, moderate N addition facilitated the photosynthetic characteristics of dominant species, but excessive N addition inhibited photosynthetic characteristics. The most appropriate N addition for the growth of L. chinensis was 5-10 g N·m-2·a?1 in the temperate steppe of Nei Mongol, China.

Key words: nitrogen addition, temperate grassland, Leymus chinensis, photosynthetic characteristics, photo- synthetic pigments