Abstract
Atmospheric CO2 (ca) has increased since the last glacial period, increasing photosynthetic water use efficiency and improving plant productivity. Evolution of C4 photosynthesis at low ca led to decreased stomatal conductance (gs), which provided an advantage over C3 plants that may be reduced by rising ca. Using controlled environments, we determined how increasing ca affects C4 water use relative to C3 plants. Leaf gas exchange and mass per area (LMA) were measured for four C3 and four C4 annual, crop-related grasses at glacial (200), ambient (400), and super-ambient (640 μmol mol−1) ca. C4 plants had lower gs, which resulted in a water use efficiency advantage at all ca and was broadly consistent with slower stomatal responses to shade, indicating less pressure on leaf water status. At glacial ca, A and LMA were lower for C3 than C4 leaves, and C3 and C4 grasses decreased leaf hydraulic conductance (Kleaf) similarly, but only C4 leaves decreased osmotic potential at turgor-loss. Greater carbon availability in C4 leaves at glacial ca generated different hydraulic adjustment relative to C3 plants. At current and future ca, C4 grasses have advantages over C3 grasses due to lower gs, lower stomatal sensitivity, and higher absolute water use efficiency.
Original language | English |
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Pages (from-to) | 2731-2741 |
Number of pages | 11 |
Journal | Journal of Experimental Botany |
Volume | 69 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2018 |
Open Access - Access Right Statement
© The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Experimental Biology. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Keywords
- carbon dioxide
- gas exchange in plants
- photosynthesis