Effects of CO₂ on Stomatal Conductance: Do Stomata Open at Very High CO₂ Concentrations?

• Published in: Annals of botany 1999-03, Vol.83 (3), p.243-251
• Main Authors: WHEELER, RAYMOND M., MACKOWIAK, CHERYL L., YORIO, NEIL C., SAGER, JOHN C.
• Format: Article
• Language: English
• Subjects: Biomass; Carbon dioxide; Carbon Dioxide - metabolism; Carbon Dioxide - pharmacology; Dose-Response Relationship, Drug; Environment, Controlled; Glycine max - cytology; Glycine max - drug effects; Glycine max - growth & development; Glycine max - metabolism; Guard cells; Life Sciences (General); Photophase; Plant Epidermis - cytology; Plant Epidermis - drug effects; Plant Epidermis - growth & development; Plant Epidermis - metabolism; Plant growth; Plant Leaves - cytology; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Transpiration - drug effects; Plants; Potatoes; Scotophase; Solanaceae - cytology; Solanaceae - drug effects; Solanaceae - growth & development; Solanaceae - metabolism; Solanum tuberosum - cytology; Solanum tuberosum - drug effects; Solanum tuberosum - growth & development; Solanum tuberosum - metabolism; Soybeans; Stomatal conductance; Triticum - cytology; Triticum - drug effects; Triticum - growth & development; Triticum - metabolism; Water - metabolism; Water consumption
• ISSN: 0305-7364; 1095-8290
• DOI: 10.1006/anbo.1998.0813

Potato and wheat plants were grown for 50 d at 400, 1000 and 10000 µmol mol⁻¹ carbon dioxide (CO₂), and sweetpotato and soybean were grown at 1000 µmol mol⁻¹ CO₂ in controlled environment chambers to study stomatal conductance and plant water use. Lighting was provided with fluorescent lamps as a 12 h photoperiod with 300 µmol m⁻² s⁻¹ PAR. Mid-day stomatal conductances for potato were greatest at 400 and 10000 µmolmol⁻¹ and least at 1000 µmol mol⁻¹ CO₂. Mid-day conductances for wheat were greatest at 400 µmol mol⁻¹ and least at 1000 and 10000 µmol mol⁻¹ CO₂. Mid-dark period conductances for potato were significantly greater at 10000 µmol mol⁻¹ than at 400 or 1000 µmol mol⁻¹, whereas dark conductance for wheat was similar in all CO₂ treatments. Temporarily changing the CO₂ concentration from the native 1000 µmol mol⁻¹ to 400 µmol mol⁻¹ increased mid-day conductance for all species, while temporarily changing from 1000 to 10000 µmol mol⁻¹ also increased conductance for potato and sweetpotato. Temporarily changing the dark period CO₂ from 1000 to 10000 µmol mol⁻¹ increased conductance for potato, soybean and sweetpotato. In all cases, the stomatal responses were reversible, i.e. conductances returned to original rates following temporary changes in CO₂ concentration. Canopy water use for potato was greatest at 10000, intermediate at 400, and least at 1000 µmol mol⁻¹ CO₂ whereas canopy water use for wheat was greatest at 400 and similar at 1000 and 10000 µmol mol⁻¹ CO₂. Elevated CO₂ treatments (i.e. 1000 and 10000 µmol mol⁻¹) resulted in increased plant biomass for both wheat and potato relative to 400 µmol mol⁻¹, and no injurious effects were apparent from the 10000 µmol mol⁻¹ treatment. Results indicate that super-elevated CO₂ (i. e. 10000 µmol mol⁻¹) can increase stomatal conductance in some species, particularly during the dark period, resulting in increased water use and decreased water use efficiency.