Elevated atmospheric CO2 improved Sorghum plant water status by ameliorating the adverse effects of drought

G. W. Wall, T. J. Brooks, N. R. Adam, A. B. Cousins, B. A. Kimball, P. J. Pinter, R. L. LaMorte, J. Triggs, M. J. Ottman, S. W. Leavitt, A. D. Matthias, D. G. Williams, A. N. Webber

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135 Scopus citations


The interactive effects of atmospheric CO2 concentration and soil-water content on grain sorghum (Sorghum bicolor) are reported here. Sorghum plants were exposed to ambient (control) and free-air CO2 enrichment (FACE; ambient + 200 μmol mol-1), under ample (wet, 100% replacement of evapo-transpiration) and reduced (dry, postplanting and mid-season irrigations) water supply over two growing seasons. FACE reduced seasonal average stomatal conductance (g5) by 0.17 mol (H2O) m-2 s-1 (32% and 37% for dry and wet, respectively) compared with control; this was similar to the difference between dry and wet treatments. FACE increased net assimilation rate (A) by 4.77 μmol (CO2) m-2s-1 (23% and 9% for dry and wet, respectively), whereas dry decreased A by 10.50 μmol (CO2) m-2s-1 (26%) compared with wet. Total plant water potential (Ψw) was 0.16 MPa (9%) and 0.04 MPa (3%) less negative in FACE than in the control treatment for dry and wet, respectively. Under dry, FACE stimulated final shoot biomass by 15%. By ameliorating the adverse effects of drought, elevated atmospheric CO2 improved plant water status, which indirectly caused an increase in carbon gain.

Original languageEnglish (US)
Pages (from-to)231-248
Number of pages18
JournalNew Phytologist
Issue number2
StatePublished - 2001


  • Carbon dioxide
  • Free-air CO enrichment (FACE)
  • Global change
  • Net assimilation rate
  • Stomatal conductance
  • Water relations

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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