植物生态学报 ›› 2017, Vol. 41 ›› Issue (2): 196-208.DOI: 10.17521/cjpe.2016.0128

• 研究论文 • 上一篇    下一篇

氮添加对内蒙古温带草原羊草光合特性的影响

翟占伟1, 龚吉蕊1,*(), 罗亲普1, 潘琰1, 宝音陶格涛2, 徐沙1, 刘敏1, 杨丽丽1   

  1. 1北京师范大学地表过程与资源生态国家重点实验室, 北京师范大学地理科学学部资源学院, 北京 100875
    2内蒙古大学生命科学学院, 呼和浩特 010021
  • 收稿日期:2016-04-07 接受日期:2016-12-25 出版日期:2017-02-10 发布日期:2017-03-16
  • 通讯作者: 龚吉蕊
  • 作者简介:* 通信作者Author for correspondence (E-mail:sunzhiqiang1956@sina.com)
  • 基金资助:
    国家自然科学基金(41571048)、国家重点基础研究发展计划(973计划) (2014CB138803)和国家重点研发计划(2016YFC0500502)

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: kangjingyao_nj@163.com

摘要:

受人类活动和气候变化的影响, 大气氮(N)沉降日益加剧, 使得草地生态系统正从自然N限制转向富营养化甚至饱和, 进而影响了草地的生长。然而, 关于优势种植物在N添加下的光合生理潜在机制的研究仍然不足。该研究以内蒙古温带典型草原优势种植物为研究对象, 通过不同水平的N养分添加实验, 探讨优势种羊草(Leymus chinensis)对N添加的光合生理响应机制。结果表明: 地上生物量随着N添加先增加后降低, 以10 g N·m-2·a?1处理增加最多。尽管25 g N·m-2·a?1处理出现下降趋势, 但与对照相比仍然显著增加了地上生物量。低N时, 植物通过把较少的N分配给羧化系统, 并降低比叶质量(LMA)使叶片获得更多的光能来适应低N生境。适量的N添加通过增加总叶绿素(Chl)的含量, 降低Chl a/b的比值来捕获更多光能; 同时增加LMA、羧化效率、最大羧化速率(Vcmax)、最大电子传递速率(Jmax), 并降低Jmax/Vcmax, 把更多的N分配给羧化系统, 提高羧化能力; 通过增加实际光化学效率、电子传递效率和光化学猝灭系数, 提高了光系统II (PSII)的光化学活性。过量的N添加对羊草的生理指标有一定抑制作用, 羧化能力降低, 导致净光合速率有所降低, 在一定程度上抑制PSII的光化学活性, 而非光化学猝灭系数以及类胡萝卜素增加起到了耗散过剩激发能的作用。N添加对羊草光合特性的影响总体表现为“适量促进, 过量抑制”。该地区羊草最适的N添加范围是5-10 g N·m-2·a?1

关键词: 氮添加, 温带草原, 羊草, 光合特性, 光合色素

Abstract:

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