Article,

CO2 enrichment increases water-use efficiency in sorghum

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New Phytologist, 151 (2): 407--412 (Aug 1, 2001)
DOI: 10.1046/j.1469-8137.2001.00184.x

Abstract

* • Sorghum (Sorghum bicolor) was grown for two consecutive seasons at Maricopa, AZ, USA, using the free-air CO2 enrichment (FACE) approach to investigate evapotranspiration of this C4 plant at ample and limited water supplies. * • Crop evapotranspiration (ET) was measured using two CO2 concentrations (control, c. 370 µmol mol−1; FACE, ambient +200 µmol mol−1) and 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 CO2 reduced 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 CO2 enrichment, 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-CO2 environment, water requirements for irrigated sorghum will be lower than at present, while dry-land productivity will increase, provided global warming is minimal.

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