Scope
Where this method applies
Use with a suitable infrared or contact method on defined leaves and canopy positions.
Environment measurement · THC SOP
Leaf Temperature Measurement
Collect repeatable leaf-temperature observations and the context needed to compare them with air conditions or use them in vapor-pressure analysis.
Frequency
When to run it
Use during environmental characterization, lighting changes, VPD investigations, heat-stress investigations, or other studies where leaf-to-air temperature difference matters.
Preparation
Tools and preconditions
Required tools
- appropriate infrared thermometer, thermal device, or contact sensor
- air temperature/RH measurement
- leaf/location labels
- record sheet
Before starting
- Know the instrument's distance, target-size, emissivity, or contact requirements.
- Avoid measuring a leaf surface that has just been handled, wetted, or shaded by the operator if that changes the intended condition.
Procedure
Run the method in order
Step 1
Define sample positions
Choose and label repeatable canopy positions or leaf classes rather than selecting only visually convenient leaves.
Record: Record plant/zone and leaf position.
Step 2
Record air context
Record nearby air temperature and RH at approximately the same time.
Record: Record air temperature, RH, sensor location, and time.
Step 3
Measure leaf surface
Use the device according to its targeting requirements and record a stable leaf-temperature value.
Record: Record leaf temperature and instrument/method.
Step 4
Repeat
Measure the planned number of positions and retain the individual values before summarizing them.
Record: Record each observation and any excluded measurement with reason.
Step 5
Summarize
Report the range and representative values together with the air measurements and canopy locations.
Record: Record summary and leaf-to-air differences when relevant.
Quality control
Verification checks
Measurement method and target location are documented.
Air temperature is measured close enough in time and space to support comparison.
Individual leaf values remain available behind any average.
Evidence record
Fields to preserve
- plant/zone
- leaf position
- leaf temperature
- air temperature
- RH
- instrument
- time
- notes
Interpretation boundary
Limitations
Infrared measurements depend on target size, viewing geometry, surface properties, and instrument configuration; a distant spot measurement can include background rather than only leaf tissue.
Connected learning