
%0 Journal Article
%A Ghannoum, Oula 
%A von Caemmerer, Susanne 
%A Conroy, Jann P. 
%T Plant water use efficiency of 17 Australian NAD-ME and NADP-ME C<emph type="8">4</emph> grasses at ambient and elevated CO<emph type="8">2</emph> partial pressure
%J Functional Plant Biology
%D 2001/12/13
%V 28
%N 12
%P 1207-1217
%K C4 photosynthesis, CO2 enrichment, NAD&#8211;ME, NADP&#8211;ME, water-use efficiency.
%R https://doi.org/10.1071/PP01056
%U https://www.publish.csiro.au/paper/PP01056 
%X This study investigates the response to elevated CO2 partial pressure (pCO2) of C4grasses belonging to different biochemical subtypes (NAD&#8211;ME and NADP&#8211;ME), and taxonomic groups (main Chloroid assemblage, Paniceae and Andropogoneae). Seventeen C4 grasses were grown under well-watered conditions in two glasshouses maintained at an average dailyppCO2 of 42 (ambient) or 68 (elevated) Pa. Elevated pCO2 significantly increased plant water-use efficiency (WUE; dry matter gain per unit water transpired) in 12 out of the 17 C4 grasses, by an average of 33%. In contrast, only five species showed a significant growth stimulation. When all species are considered, the average plant dry mass enhancement at elevated pCO2 was 26%. There were no significant subtype (or taxa) &#215; pCO2 interactions on either WUE or biomass accumulation. When leaf gas exchange was compared at growth pCO2 but similar light and temperature, high pCO2-grown plants had similar CO2 assimilation rates (A) but a 40% lower stomatal conductance than their low pCO2-grown counterparts. There were no signs of either photosynthetic or stomatal acclimation in any of the measured species. We conclude that elevated pCO2 improved WUE primarily by reducing stomatal conductance. 
