CO2Enrichment Increases Water-Use Efficiency in Sorghum

• Published in: The New phytologist 2001-08, Vol.151 (2), p.407-412
• Main Authors: Conley, Matthew M., Kimball, B. A., Brooks, T. J., Pinter, P. J., Hunsaker, D. J., Wall, G. W., Adam, N. R., LaMorte, R. L., Matthias, A. D., Thompson, T. L., Leavitt, S. W., Ottman, M. J., Cousins, A. B., Triggs, J. M.
• Format: Article
• Language: English
• Subjects: Agriculture; Carbon dioxide; Drought; Evapotranspiration; Irrigation; Irrigation water; Plants; Soil water; Soil water content; Sorghum
• ISSN: 0028-646X; 1469-8137

• Sorghum (Sorghum bicolor) was grown for two consecutive seasons at Maricopa, AZ, USA, using the free-air CO2enrichment (FACE) approach to investigate evapotranspiration of this C4 plant at ample and limited water supplies. • Crop evapotranspiration (ET) was measured using two CO2concentrations (control, c. 370 μmol mol-1FACE, ambient +200 μmol mol-1and two irrigation treatments (well watered and water-limited). Volumetric soil water content was measured before and after each irrigation using neutron scattering techniques. • Averaged over both years, elevated CO2reduced cumulative ET by 10% when plants were given ample water and by 4% under severe drought stress. Water-use efficiency based on grain yield (WUE-G) increased, due to CO2enrichment, by 9% and 19% in wet and dry plots, respectively; based on total biomass, water-use efficiency (WUE-B) increased by 16% and 17% in wet and dry plots, respectively. • These data suggest that in the future high- CO2environment, water requirements for irrigated sorghum will be lower than at present, while dry-land productivity will increase, provided global warming is minimal.