Increased C availability at elevated carbon dioxide concentration improves N assimilation in a legume

Alistair Rogers, Yves Gibon, Mark Stitt, Patrick B. Morgan, Carl J. Bernacchi, Donald R. Ort, Stephen P. Long

Research output: Contribution to journalArticlepeer-review


Plant growth is typically stimulated at elevated carbon dioxide concentration ([CO2]), but a sustained and maximal stimulation of growth requires acquisition of additional N in proportion to the additional C fixed at elevated [CO2]. We hypothesized that legumes would be able to avoid N limitation at elevated [CO2]. Soybean was grown without N fertilizer from germination to final senescence at elevated [CO2] over two growing seasons under fully open-air conditions, providing a model legume system. Measurements of photosynthesis and foliar carbohydrate content showed that plants growing at elevated [CO2] had a c. 25% increase in the daily integral of photosynthesis and c. 58% increase in foliar carbohydrate content, suggesting that plants at elevated [CO2] had a surplus of photosynthate. Soybeans had a low leaf N content at the beginning of the season, which was a further c. 17% lower at elevated [CO2]. In the middle of the season, ureide, total amino acid and N content increased markedly, and the effect of elevated [CO2] on leaf N content disappeared. Analysis of individual amino acid levels supported the conclusion that plants at elevated [CO2] overcame an early-season N limitation. These soybean plants showed a c. 16% increase in dry mass at final harvest and showed no significant effect of elevated [CO2] on leaf N, protein or total amino acid content in the latter part of the season. One possible explanation for these findings is that N fixation had increased, and that these plants had acclimated to the increased N demand at elevated [CO2].

Original languageEnglish (US)
Pages (from-to)1651-1658
Number of pages8
JournalPlant, Cell and Environment
Issue number8
StatePublished - Aug 1 2006


  • Amino acids
  • Carbohydrate
  • Elevated CO
  • Free air CO enrichment (FACE)
  • Legumes
  • Ureides

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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