Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2015
Publication Date: 7/23/2015
Citation: Gitz, D.C., Baker, J.T., Lascano, R.J. 2015. Relating xylem cavitation to gas exchange in cotton. American Journal of Plant Sciences. 6(11):1742-1751.
Interpretive Summary: Plants draw water from the ground through their stems and out their leaves. The water in the stems is drawn through tiny capillary tubes called xylem. When the plant is stressed by drought the water columns in the xylem snap and make faint ultrasonic clicks. We found that with the right instruments we can listen to the plants and they will tell us when they need water. This will be important for controlling irrigation and will allow us to grow more with less water.
Technical Abstract: Acoustic emissions (AEs) from xylem cavitation events are characteristic of transpiration processes. Though a body of work using AE exists with a large number of species, cotton and other agronomically important crops have either not been investigated, or limited information exists. The objective of this work was to relate AEs to drought stress in cotton. Glasshouse grown cotton (cvar FM 958) was grown in mini-lysimeters and instrumented with a portable photosynthesis system and ultrasonic transducers interfaced with a digital signal-processing unit. Whole plant transpiration, leaf level gas exchange and ultrasonic AEs were measured. Results revealed xylem cavitation events temporally associated with the onset of drought stress. The results suggest that stoma close in response to reduced hydraulic conductance from xylem cavitation events. This technique shows promise as a refinement of existing irrigation control systems based on canopy temperatures perhaps eliminating the need for empirically determined ambient humidity control algorithms.