Elevated CO2 increases water use efficiency by sustaining photosynthesis of water-limited maize and sorghum

Publication year: 2011
Source: Journal of Plant Physiology, In Press, Corrected Proof, Available online 14 June 2011

Leon Hartwell, Allen Jr. , Vijaya Gopal, Kakani , Joseph C.V., Vu , Kenneth J., Boote

Maize and grain sorghum seeds were sown in pots and grown for 39 days in sunlit controlled-environment chambers at 360 (ambient) and 720 (double-ambient, elevated)μmolmol−1 carbon dioxide concentrations [CO2]. Canopy net photosynthesis (PS) and evapotranspiration (TR) was measured throughout and summarized daily from 08:00 to 17:00h Eastern Standard Time. Irrigation was withheld from matched pairs of treatments starting on 26 days after sowing (DAS). By 35 DAS, cumulative PS of drought-stress maize, compared to well-watered plants, was 41% lower under ambient [CO2] but only 13% lower under elevated [CO2]. In contrast, by 35 DAS, cumulative PS of drought-stress grain sorghum,…