Microtensiometers Accurately Measure Stem Water Potential in Woody Perennials

Area of Science:

• Plant Physiology
• Agricultural Science
• Environmental Science

Background:

• Stem water potential (Ψstem) is a standard plant water status indicator.
• Current measurement using pressure chambers (PC) is not continuous or automated.
• Microtensiometers (MT) offer potential for continuous water tension monitoring in trees.

Purpose of the Study:

• Validate microtensiometers (MT) for measuring stem water potential (Ψstem).
• Compare continuous MT measurements with discrete pressure chamber (PC) data.
• Assess the utility of MT in dynamic plant water relation studies.

Main Methods:

• Applied control and deficit irrigation to pear trees (Pyrus communis L.).
• Collected discrete data on leaf gas exchange, canopy temperature, and Ψstem using PC and MT.
• Recorded measurements every two hours over four days from dawn to sunset.

Main Results:

• Strong linear relationships observed between MT and PC stem water potential (R² > 0.8).
• MT stem water potential showed strong correlation with vapor pressure deficit (R² > 0.7).
• MT data exhibited increased variability and lower values than PC below -1.5 MPa, particularly in the evenings.

Conclusions:

• Microtensiometers (MT) show significant potential for continuous assessment of tree water status.
• MT measurements correlate well with pressure chamber (PC) data, offering a viable alternative for dynamic monitoring.
• Further research can refine MT use for comprehensive plant water relation analysis.