Abstract
The interactive effects of atmospheric CO2 concentration and soil-water content on grain sorghum (Sorghum bicolor) are reported here. Sorghum plants were exposed to ambient (control) and free-air CO2 enrichment (FACE; ambient + 200 μmol mol-1), under ample (wet, 100% replacement of evapo-transpiration) and reduced (dry, postplanting and mid-season irrigations) water supply over two growing seasons. FACE reduced seasonal average stomatal conductance (g5) by 0.17 mol (H2O) m-2 s-1 (32% and 37% for dry and wet, respectively) compared with control; this was similar to the difference between dry and wet treatments. FACE increased net assimilation rate (A) by 4.77 μmol (CO2) m-2s-1 (23% and 9% for dry and wet, respectively), whereas dry decreased A by 10.50 μmol (CO2) m-2s-1 (26%) compared with wet. Total plant water potential (Ψw) was 0.16 MPa (9%) and 0.04 MPa (3%) less negative in FACE than in the control treatment for dry and wet, respectively. Under dry, FACE stimulated final shoot biomass by 15%. By ameliorating the adverse effects of drought, elevated atmospheric CO2 improved plant water status, which indirectly caused an increase in carbon gain.
Original language | English (US) |
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Pages (from-to) | 231-248 |
Number of pages | 18 |
Journal | New Phytologist |
Volume | 152 |
Issue number | 2 |
DOIs | |
State | Published - Nov 13 2001 |
Keywords
- Carbon dioxide
- Free-air CO enrichment (FACE)
- Global change
- Net assimilation rate
- Stomatal conductance
- Water relations
ASJC Scopus subject areas
- Physiology
- Plant Science