| Abstrakt: |
The elevated CO2 concentration (eCO2) is expected to improve plant water relations and carbon (C) uptakes, with a potential to mitigate drought stress. However, the interactive effects of eCO2 and drought on plant physiology and growth are not clear.We performed a meta‐analysis on the interactive effects of eCO2 and drought on plant water relations, photosynthesis, biomass production and allocation.We found that eCO2 did not lead to the conservation of soil water, but improved leaf water status under drought conditions as evidenced by a higher leaf relative water content (LRWC) and a less negative midday leaf water potential, resulting from reduced stomatal conductance (gs) and increased root to shoot ratio. Elevated CO2 retarded the response of gs to drought, which may be mediated by the decrease in leaf abscisic acid concentration under eCO2 and drought. Drought imposed stomatal limitations on photosynthesis (A), which was alleviated by eCO2 via increasing intercellular CO2 concentration (Ci). This led to a stronger A response to eCO2 under drought, supporting the 'low Ci effect'. However, no interaction of eCO2 and drought was detected on plant biomass production. Intrinsic water use efficiency (iWUE) increased proportionally with eCO2, while plant‐scale WUE was less responsive to eCO2. C3 plants had advantages over C4 plants in terms of A and biomass production under eCO2 and well‐watered conditions rather than under eCO2 and drought conditions. Drought caused a greater reduction in biomass for woody plants than for herbs. Plants growing in pots showed greater decreases in the physiology and biomass under drought than those growing in field.Synthesis. These findings suggest that eCO2 can alleviate the adverse impacts of drought on plant water relations and C sequestration, and are of significance in the prediction of plant growth and ecosystem productivity under global changes. [ABSTRACT FROM AUTHOR] |
Plný text