Does elevated CO₂ protect photosynthesis from damage by high temperature via modifying leaf water status in maize seedlings?

• Published in: Photosynthetica 2014, Vol.52 (2), p.211-216
• Main Authors: Qu, M. N, Bunce, J. A, Shi, Z. S
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; carbon dioxide; corn; high temperature treatment; leaf water potential; leaves; Life Sciences; long term effects; photosynthesis; Plant Physiology; seedlings; stomatal conductance; temperature; Zea mays
• ISSN: 0300-3604; 1573-9058
• DOI: 10.1007/s11099-014-0022-0

We hypothesized that decreased stomatal conductance (g ₛ) at elevated CO₂ might decrease transpiration (E), increase leaf water potential (ΨW), and thereby protect net photosynthesis rate (P N) from heat damage in maize (Zea mays L) seedlings. To separate long-term effects of elevated CO₂, plants grew at either ambient CO₂ or elevated CO₂. During high-temperature treatment (HT) at 45°C for 15 min, leaves were exposed either to ambient CO₂ (380 μmol mol⁻¹) or to elevated CO₂ (560 μmol mol⁻¹). HT reduced P N by 25 to 38% across four CO₂ combinations. However, the g ₛ and E did not differ among all CO₂ treatments during HT. After returning the leaf temperature to 35°C within 30 min, g ₛ and E were the same or higher than the initial values. Leaf water potential (ΨW) was slightly lower at ambient CO₂, but not at elevated CO₂. This study highlighted that elevated CO₂ failed in protecting P N from 45°C via decreasing g ₛ and ΨW.