植物生态学报 ›› 2026, Vol. 50 ›› Issue (2): 429-441.DOI: 10.17521/cjpe.2025.0063  cstr: 32100.14.cjpe.2025.0063

• 研究论文 • 上一篇    下一篇

不同水平氮添加下晋北赖草叶片化学计量特征及其对光合的影响

贾会丽1,2,3(), 王睿1,2,3, 常玉良1,2,3, 林茂1,2,3, 栗国梁1,2,3, 武帅楷1,2,3, 苏原1,2,3, 董宽虎1,2,3, $\boxed{\hbox{王常慧}}$1,2,3   

  1. 1 山西农业大学草业学院, 山西太谷 030801
    2 草地生态保护与乡土草种质创新山西省重点实验室, 山西太谷 030801
    3 山西右玉黄土高原草地生态系统国家定位观测研究站, 山西右玉 037200
  • 收稿日期:2025-02-24 接受日期:2025-06-09 出版日期:2026-02-28 发布日期:2026-04-01
  • 作者简介:贾会丽 E-mail: jiahuilisxau@126.com
    第一联系人:*同等贡献
  • 基金资助:
    山西省基础研究计划(20210302123406);国家自然科学基金(U22A20576);山西省重点实验室项目(202104010910017)

Stoichiometric characteristics of Leymus secalinus under different levels of nitrogen addition and its effects on photosynthesis

JIA Hui-Li1,2,3(), WANG Rui1,2,3, CHANG Yu-Liang1,2,3, LIN Mao1,2,3, LI Guo-Liang1,2,3, WU Shuai-Kai1,2,3, SU Yuan1,2,3, DONG Kuan-Hu1,2,3, $\boxed{\hbox{WANG Chang-Hui}}$1,2,3   

  1. 1 College of Grassland Science, Shanxi Agricultural University, Taigu, Shanxi 030801, China
    2 Shanxi Key Laboratory of Grassland Ecological Protection and Native Grass Germplasm Innovation, Taigu, Shanxi 030801, China
    3 and Youyu Loess Plateau Grassland Ecosystem National Research Station, Youyu, Shanxi 037200, China
  • Received:2025-02-24 Accepted:2025-06-09 Online:2026-02-28 Published:2026-04-01
  • About author:First author contact:*Contributed equally to this work
  • Supported by:
    Fundamental Research Program of Shanxi Province(20210302123406);National Natural Science Foundation of China(U22A20576);Key Laboratory Project of Shanxi Province(202104010910017)

摘要:

研究晋北赖草(Leymus secalinus)草地叶片碳含量(LCC)、氮含量(LNC)与光合特性对不同水平氮添加的响应对于开展氮沉降背景下晋北农牧交错带草地可持续利用有重要意义。然而, 关于氮添加下LCC、LNC与光合特性的饱和阈值是否一致以及相互作用的潜在机制尚不清楚。该研究以晋北赖草草地为研究对象, 设置8个氮添加水平(0、1、2、4、8、16、24、32 g·m-2·a-1), 测定赖草叶片形态指标、LCC、LNC、色素含量和光合特性, 并计算氮饱和阈值以及氮响应效率。结果表明: (1)单位叶质量氮含量(LNCmass)和单位叶面积氮含量(LNCarea)随氮添加水平呈现logistic生长曲线变化, 饱和阈值分别为11.41和7.20 g·m-2·a-1。单位叶质量碳氮比(C:N)和单位叶面积碳氮比(LCCarea:LNCarea)随氮添加水平呈幂函数降低。(2)叶片形态指标(叶长(LL)、叶宽(LW)、叶厚(LT)、叶面积(LA))、色素含量(叶绿素a、b、类胡萝卜素和总叶绿素含量)和光合特性参数(净光合速率(Pn)和蒸腾速率(Tr))随氮添加水平呈先增加后降低的分段线性模式, Pn的氮饱和响应阈值为16 g·m-2·a-1; 而气孔限制值(Ls)和水分利用效率(WUE)则呈相反的变化模式。(3) LCC、LNC和Pn的氮响应效率(NRELCC、NRELNC、NREPn)随氮添加水平呈指数下降趋势。(4)结构方程模型结果显示, Pn受LCC和LNC间接调控且低氮和高氮添加下的调控机制不同。低氮添加下, LCC和LNC通过调控叶片形态特征介导对Pn的调控; 而高氮添加下, Pn的调控通过LNC调控叶面积和叶绿素含量来实现。研究表明不同水平氮添加下晋北赖草草地植物叶片碳氮含量呈非线性变化, 而叶片光合特性呈线性变化; 低氮添加有利于促进植物叶片碳、氮含量的积累和光合作用的增强。综上, 该研究发现了不同水平氮添加下晋北赖草草地植物叶片LCC、LNC呈非线性响应, 而光合特性呈线性响应特征, 并探究了LCC、LNC对叶片光合的调控机制。

关键词: 氮沉降, 碳含量, 氮含量, 净光合速率, 氮响应效率, 响应阈值

Abstract:

Aims Studying the response of leaf carbon content (LCC) and nitrogen content (LNC), as well as photosynthetic characteristics, to varying levels of nitrogen addition in Leymus secalinus grasslands in northern Shanxi holds significant importance for the sustainable utilization of grasslands in the agro-pastoral ecotone under the backdrop of nitrogen (N) deposition. However, whether the saturation threshold of LCC and LNC to N addition is the same as leaf photosynthetic characteristics and their potential mechanism of the interaction are not clear.

Methods This study focused on the Leymus secalinus grassland in northern Shanxi, across eight N addition levels (0, 1, 2, 4, 8, 16, 24, 32 g·m-2·a-1). Morphological characteristics, LCC and LNC, pigment content and the photosynthetic characteristics of Leymus secalinus leaves were measured. N saturation threshold and N response efficiency of LCC and LNC, as well as net photosynthetic rate were also calculated.

Important findings The results showed that: (1) N content per unit leaf mass (LNCmass) and per unit leaf area (LNCarea) of L. secalinus showed a logistic growth curve with the increase of N addition level. The N saturation response thresholds of LNCmass and LNCarea were 11.41 and 7.20 g·m-2·a-1, respectively. C:N of per unit leaf mass (C:N) and C:N of per unit leaf area (LCCarea:LNCarea) of L. secalinus decreased in power function with the increase of N addition level. (2) Morphological characteristics (leaf length (LL), leaf width (LW), leaf thickness (LT), leaf area (LA)), Pigment content (chlorophyll a content (Ca), chlorophyll b content (Cb), total chlorophyll content (Chl), carotenoids (Car)), photosynthetic characteristics (net photosynthetic rate (Pn), transpiration rate (Tr)) of L. secalinus showed the piecewise linear mode of first increasing and then decreasing with the increase of N addition level, and the N saturation response threshold of Pn was 16 g·m-2·a-1. However, the stomatal limit value (Ls) and water use efficiency (WUE) changed in the opposite pattern. (3) N response efficiencies of LCC, LNC and Pn (NRELCC, NRELNC, NREPn) decreased exponentially with the increase of N addition level. (4) Structural equation modeling results showed that Pn was indirectly regulated by LCC and LNC, and the regulation mechanism was different under low N and high N addition treatments. LCC and LNC mediate the regulation of Pn by regulating leaf morphological characteristics at low N addition level; the regulation of Pn was achieved by regulating leaf area and chlorophyll content by LNC at high N addition level. This study showed that LCC and LNC showed nonlinear response, while the photosynthetic characteristics showed linear response characteristics under different levels of N addition. We also explored the regulatory mechanisms of LCC and LNC on photosynthesis.

Key words: nitrogen deposition, carbon content, nitrogen content, net photosynthetic rate, nitrogen response efficiency, response threshold