Gas exchange and water-use efficiency in plant canopies

Cernusak, L.A. (2020) Gas exchange and water-use efficiency in plant canopies. Plant Biology, 22 (S1). pp. 52-67.

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In this review, I first address the basics of gas exchange, water-use efficiency and carbon isotope discrimination in C(3)plant canopies. I then present a case study of water-use efficiency in northern Australian tree species. In general, C(3)plants face a trade-off whereby increasing stomatal conductance for a given set of conditions will result in a higherCO(2)assimilation rate, but a lower photosynthetic water-use efficiency. A common garden experiment suggested that tree species which are able to establish and grow in drier parts of northern Australia have a capacity to use water rapidly when it is available through high stomatal conductance, but that they do so at the expense of low water-use efficiency. This may explain why community-level carbon isotope discrimination does not decrease as steeply with decreasing rainfall on the North Australian Tropical Transect as has been observed on some other precipitation gradients. Next, I discuss changes in water-use efficiency that take place during leaf expansion in C(3)plant leaves. Leaf phenology has recently been recognised as a significant driver of canopy gas exchange in evergreen forest canopies, and leaf expansion involves changes in both photosynthetic capacity and water-use efficiency. Following this, I discuss the role of woody tissue respiration in canopy gas exchange and how photosynthetic refixation of respiredCO(2)can increase whole-plant water-use efficiency. Finally, I discuss the role of water-use efficiency in driving terrestrial plant responses to global change, especially the rising concentration of atmosphericCO(2). In coming decades, increases in plant water-use efficiency caused by risingCO(2)are likely to partially mitigate impacts on plants of drought stress caused by global warming.

Item ID: 65829
Item Type: Article (Research - C1)
ISSN: 1438-8677
Copyright Information: © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands. The author accepted manuscript may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP0991427, ARc FT100100329
Date Deposited: 04 Feb 2021 02:32
FoR Codes: 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 100%
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