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Elevated CO 2 effects on canopy and soil water flux parameters measured using a large chamber in crops grown with free‐air CO 2 enrichment
Author(s) -
Burkart S.,
Manderscheid R.,
Wittich K.P.,
Löpmeier F. J.,
Weigel H.J.
Publication year - 2011
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/j.1438-8677.2010.00360.x
Subject(s) - transpiration , canopy , vapour pressure deficit , growing season , canopy conductance , microclimate , agronomy , sugar beet , environmental science , stomatal conductance , leaf area index , hordeum vulgare , evapotranspiration , horticulture , atmospheric sciences , poaceae , biology , botany , photosynthesis , ecology , geology
An arable crop rotation (winter barley–sugar beet–winter wheat) was exposed to elevated atmospheric CO 2 concentrations ([CO 2 ]) using a FACE facility (Free‐Air CO 2 Enrichment) during two rotation periods. The atmospheric [CO 2 ] of the treatment plots was elevated to 550 ppm during daylight hours (T > 5 °C). Canopy transpiration (E C ) and conductance (G C ) were measured at selected intervals (>10% of total growing season) using a dynamic CO 2 /H 2 O chamber measuring system. Plant available soil water content (gravimetry and TDR probes) and canopy microclimate conditions were recorded in parallel. Averaged across both growing seasons, elevated [CO 2 ] reduced E C by 9%, 18% and 12%, and G C by 9%, 17% and 12% in barley, sugar beet and wheat, respectively. Both global radiation (Rg) and vapour pressure deficit (VPD) were the main driving forces of E C , whereas G C was mostly related to Rg. The responses of E C and especially G C to [CO 2 ] enrichment were insensitive to weather conditions and leaf area index. However, differences in LAI between plots counteracted the [CO 2 ] impact on E C and thus, at least in part, explained the variability of seasonal [CO 2 ] responses between crops and years. As a consequence of lower transpirational canopy water loss, [CO 2 ] enrichment increased plant available soil water content in the course of the season by ca . 15 mm. This was true for all crops and years. Lower transpirational cooling due to a [CO 2 ]‐induced reduction of E C increased canopy surface and air temperature by up to 2 °C and 0.5 °C, respectively. This is the first study to address effects of FACE on both water fluxes at canopy scale and water status of a European crop rotation.