Limited potential of harvest index improvement to reduce methane emissions from rice paddies

Yu Jiang, Haoyu Qian, Ling Wang, Jinfei Feng, Shan Huang, Bruce A. Hungate, Chris van Kessel, William R. Horwath, Xingyue Zhang, Xiaobo Qin, Yue Li, Xiaomin Feng, Jun Zhang, Aixing Deng, Chenyan Zheng, Zhenwei Song, Shuijin Hu, Kees Jan van Groenigen, Weijian Zhang

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Rice is a staple food for nearly half of the world's population, but rice paddies constitute a major source of anthropogenic CH 4 emissions. Root exudates from growing rice plants are an important substrate for methane-producing microorganisms. Therefore, breeding efforts optimizing rice plant photosynthate allocation to grains, i.e., increasing harvest index (HI), are widely expected to reduce CH 4 emissions with higher yield. Here we show, by combining a series of experiments, meta-analyses and an expert survey, that the potential of CH 4 mitigation from rice paddies through HI improvement is in fact small. Whereas HI improvement reduced CH 4 emissions under continuously flooded (CF) irrigation, it did not affect CH 4 emissions in systems with intermittent irrigation (II). We estimate that future plant breeding efforts aimed at HI improvement to the theoretical maximum value will reduce CH 4 emissions in CF systems by 4.4%. However, CF systems currently make up only a small fraction of the total rice growing area (i.e., 27% of the Chinese rice paddy area). Thus, to achieve substantial CH 4 mitigation from rice agriculture, alternative plant breeding strategies may be needed, along with alternative management.

Original languageEnglish (US)
Pages (from-to)686-698
Number of pages13
JournalGlobal change biology
Issue number2
StatePublished - Feb 1 2019


  • climate change
  • food security
  • greenhouse gases
  • meta-analysis
  • water management

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • General Environmental Science


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