Physics of cavitation bubbles and embolism in trees

On the  September 13, 2021
Dr Philippe MARMOTTANT - Grenoble LiPHY
Without a pulsating heart, plants have developed other effective strategies to circulate fluids within their internal conduits. Evapotranspiration is one of them: by accepting to lose water with their leaves, plants create very strong depressions that drive the sap towards the top of the tree. These depressions are phenomenal and result in a
negative pressure, down to -189 bar for some desert plants. A dangerous drawback of allowing negative pressures is the cavitation of the sap in case of too much drought. Cavitation is the sudden nucleation of gas bubbles, and their development into an embolism stops the circulation of sap. In this seminar, we will show that cavitation bubbles emit ultrasonic sounds and are visible in the leaves. In parallel we will address the physical principles ruling those catastrophic behaviors.
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Published on  September 4, 2021
Updated on September 9, 2021