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Desert shrubs cranked up water use efficiency to survive a megadrought. It may not be enough.

Phys.org/news (DECEMBER 20, 2021)

Titre : Desert shrubs cranked up water use efficiency to survive a megadrought. It may not be enough.

Shrubs in the desert Southwest have increased their water use efficiency at some of the highest rates ever observed to cope with a decades-long megadrought. That’s the finding of a new study from University of Utah researchers, who found that although the shrubs’ efficiency increases are unprecedented and heroic, they may not be enough to adapt to the long-term drying trend in the West. Phys.org/news (DECEMBER 20, 2021)

Présentation
The key metric to know for this study is intrinsic water-use efficiency, or iWUE. It’s a ratio of the amount of photosynthesis in a plant to how open the plants’ stomata are. Stomata are small openings in leaves that allow carbon dioxide to come in and water vapor to go out. Think of them as the plants’ nostrils.

When iWUE is high, then plants carry out photosynthesis with minimal stomatal opening. Several factors can affect a plant’s iWUE. If carbon dioxide levels in the atmosphere go up, then the plants don’t need to open their stomata as much to bring in the same amount of carbon. If temperatures rise or water availability drops, the plant will restrict stomatal opening so as to not lose too much water.

It would stand to reason, then, that current rising carbon dioxide levels and warming and drying trends would lead to increases in iWUE. But by how much ? And how does it compare to iWUE trends in the past ?

Source  : University of Utah

Annonce (Phys.org/news)

Page publiée le 15 janvier 2023