Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (4): 922-931.DOI: 10.3773/j.issn.1005-264x.2008.04.022

• Original article • Previous Articles     Next Articles


KOU Tai-Ji1,2(), ZHU Jian-Guo1,*(), XIE Zu-Bin1, LIU Gang1, ZENG Qing1   

  1. 1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
    2College of Agriculture, Henan University of Science and Technology, Luoyang, Henan 471003, China
  • Received:2006-10-11 Accepted:2007-08-11 Online:2008-10-11 Published:2008-07-30
  • Contact: ZHU Jian-Guo


Aims Understanding belowground processes will help in determining the potential feedback of soil C storage on increased atmospheric CO2 concentration. Information on root respiration and biomass are important for understanding implications of environmental change on soil carbon cycling and sequestration. Because cropland is an important terrestrial ecosystem within the global climate change context, separately quantifying the response of crop root respiration and biomass to CO2 enrichment has important implications for agro-ecosystems, for predicting the magnitude and direction of soil C feedbacks. We observe them in a field experiment and evaluate the potential effect of elevated atmospheric CO2 concentration.

Methods We used a free-air carbon dioxide enrichment (FACE) system and static chamber-GC (gas chromatography) method to study the effects of elevated atmospheric CO2 concentration and nitrogen fertilizer on root respiration and biomass of wheat (Triticum aestivum cv Yangmai 14) during two consecutive seasons, determined by a novel split root growth and gas collection system.

Important finding Both elevated CO2 concentration and high nitrogen (HN, 148.1 mg N·kg-1 dry soil weight) application enhanced above- and belowground biomass in three different growth stages. The increase in belowground biomass under elevated CO2 concentration favors more residual roots to revert to field. Elevated CO2 concentration significantly stimulated root respiration at the booting-heading stages, which increased by 33.8% and 43.9% in 2004-2005, and by 23.8% and 28.9% in 2005-2006 in both high and low nitrogen (LN, 88.9 mg N·kg-1 dry soil weight) application, respectively, and significantly depressed root respiration at the late of filling stage by 31.4% and 23.3% in 2004-2005, and by 25.1% and 18.5% in 2005-2006 in both HN and LN treatments, respectively; however, no significant effect was found at the jointing stage. High nitrogen application promoted more root respiration than low nitrogen. While a significantly negative liner correlation between root respiration rate and belowground biomass was observed, the R2 of correlative coefficient under elevated CO2 concentration was small, which showed elevated CO2 concentrationreduced the correlation of both root respiration and accumulation of belowground biomass with wheat growing.

Key words: elevated atmospheric CO2 concentration, wheat, root respiration, belowground biomass, aboveground biomass, nitrogen fertilizer