植物生态学报 ›› 2009, Vol. 33 ›› Issue (6): 1165-1176.DOI: 10.3773/j.issn.1005-264x.2009.06.017

• 研究论文 • 上一篇    下一篇

内蒙古草原3年生小叶锦鸡儿根瘤特征及其对环境变化的响应

张灿娟1,2, 吴冬秀1,*(), 张琳1,2, 展小云1,2, 周双喜1,2, 杨云霞1,2   

  1. 1 中国科学院植物研究所植被与环境变化国家重点实验室,北京 100093
    2 中国科学院研究生院,北京 100049
  • 收稿日期:2009-04-13 接受日期:2009-04-27 出版日期:2009-04-13 发布日期:2021-04-29
  • 通讯作者: 吴冬秀
  • 作者简介:*(wudx@ibcas.ac.cn
  • 基金资助:
    国家自然科学基金(30270945);中国科学院知识创新工程重要方向项目(KZCX2-YW-433-02);中国科学院野外台站研究基金项目

NODULE CHARACTERISTICS OF THREE-YEAR-OLD CARAGANA MICROPHYLLA AND THEIR RESPONSES TO ENVIRONMENTAL CHANGES IN AN INNER MONGOLIA GRASSLAND

ZHANG Can-Juan1,2, WU Dong-Xiu1,*(), ZHANG Lin1,2, ZHAN Xiao-Yun1,2, ZHOU Shuang-Xi1,2, YANG Yun-Xia1,2   

  1. 1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2009-04-13 Accepted:2009-04-27 Online:2009-04-13 Published:2021-04-29
  • Contact: WU Dong-Xiu

摘要:

小叶锦鸡儿(Caragana microphylla)是氮素匮缺的内蒙古草原的灌丛优势种, 研究其根瘤性状及其对不同环境因子的响应特征, 可以进一步了解草原生态系统共生固氮过程及其对全球变化的响应机制。在中国科学院内蒙古草原生态系统定位研究站, 利用开顶式生长室(Open-top chamber, OTC)控制实验模拟环境变化, 研究了3年生小叶锦鸡儿播种苗根瘤特征, 及其对氮素添加、干旱和加水和大气CO2浓度升高的响应。结果表明: 1) 3年生小叶锦鸡儿明显有根瘤着生, 多着生于侧根。根瘤形状多样, 以浅黄色的梨状和球状根瘤为主(占根瘤总数的68%); 另有少数棕褐色棒状和纺锤状根瘤(占根瘤总数的30%); 还有极少数较大的Y状根瘤。2)添加氮素极显著地抑制根系和根瘤的生长发育: 根系有发白现象, 且着生在其上的几乎都是干瘪根瘤。这种抑制效应随着水分增加和CO2浓度升高有所减缓。3)干旱抑制根系和根瘤生长, 而加水促进二者生长。与干旱和正常水分相比, 加水时根系更发达, 根瘤形态多样, 出现掌状和珊瑚状等大型根瘤。随着水分增加, 根瘤着生部位由主根渐向侧根再向须根发展。与正常水分相比, 减水时根瘤平均长度降低了50.4% (p<0.05); 在加水条件下根瘤生长状况最为良好, 单株根瘤数量和重量以及根瘤平均重量均显著增加。4) CO2浓度升高对根瘤生长有促进作用, 但未达到显著。5)根瘤数量对环境因子的变化比根瘤大小更敏感; 氮素和水分对单株根瘤数量和重量具有交互作用; 对于水分和氮素相对缺乏的内蒙古草原, 水分是限制小叶锦鸡儿根瘤菌侵染根系形成根瘤的关键因子。

关键词: 温带草原, 小叶锦鸡儿, 根瘤, 氮素, 水分, CO2浓度

Abstract:

Aims Caragana microphylla widely spreads in Inner Mongolia grasslands as a dominant shrubby legume. Its nodule growth has been poorly addressed. Our objective is to examine nodule characteristics and their responses to different environmental factors to provide insights into their nitrogen fixing and nitrogen cycling processes under future changing environments.

Methods We conducted a field experiment in 2008 using open-top chambers at the Inner Mongolia Grassland Ecosystem Research Station of Chinese Academy of Sciences. We examined the number, weight and length of nodules of three-year-old C. microphylla individuals and their responses to nitrogen addition, drought, water addition and elevated atmospheric CO2 concentration.

Important findings Nodules were mainly distributed in lateral roots, and most had buff or brown color. Nodule shapes were diverse, being pyriform, globular, claviform, fusiform, and Y shaped. Root growth and nodule growth were significantly inhibited under the nitrogen addition treatment, resulting in roots being whitened and most nodules dead and black-brown. Drought depressed root nodulation, with mean length of nodules decreased significantly by 50.4% compared with that under normal water supply. Water addition stimulated root growth and nodule growth. Roots nodulated best under the combined treatment of water addition, elevated CO2 and non-nitrogen addition, with maximum mean length and weight of individual nodules and the maximum nodule weight per plant. Nodules in fibers relatively increased with increasing water supply. Nodule growth did not significantly respond to elevated CO2. Nodule number is more sensitive to environmental changes than nodule size, there are significant nitrogen × water interactions on nodule number and weight per plant and the effects of three environmental factors on nodule growth are different. The negative effect of nitrogen is larger than the positive effects of water and elevated CO 2. It is inferred that water is the major factor affecting the infection of rhizobia and the generation of nodules in this semiarid grassland ecosystem.

Key words: grassland ecosystem, Caragana microphylla, nodule, nitrogen addition, soil water levels, elevated atmospheric CO2 concentration