canopy temperature sensor

  • Canopy Infrared Temperature SensorIdeal for continuous, non-contact measurements of leaf and/or plant temperature
  • 3:1 field of view (for every 3 units of distance from sensor, there is 1 unit diameter FOV)
  • Measurements are related to plant water use, drought-strategies, and nutrient uptake
  • Measure leaf-to-air temperature differences for plant physiological and research projects
  • Voltage, current or SDI-12 outputs
  • Monitor related variables such as meteorological, transpiration and soil moisture

 

related products

 

Leaf-to-Air Temperature DifferenceThe LT-IRM infrared temperature sensors offers intelligence in a rugged, easy-to-use package. The LT-IRM is centered around a high-speed microprocessor that continuously monitors and adjusts the complete system. While performing the complex algorithms determining the output, it calibrates itself about once every second, removing any concerns over drift or sudden changes.

Other advanced features include emissivity shift compensation and ambient radiation error correction. The rugged housing withstands thermal and mechanical shocks. The built-in air purge prevents dust, dirt, or condensing vapors from depositing on sensor optics, assuring long-term accuracy under all environmental conditions. The integral heat exchanger eliminates drift by automatically warming (or cooling) supply air to match the optical aperture temperature.

The delivery set includes the LT-IRM sensor with the 1-m air conduit and the air purge pump.

The output cable length should be specified in the order if required.

Every sensor is individually tested and calibrated within the measurement range.

 

more information

Canopy Temperature Measurements Explained

 

specifications
feature specification
Measurement Range 0 to 100 ℃
Absolute Accuracy ±1 ℃
Repeatability ±0.1 ℃
Output 0 to 2 V, 4..20mA, SDI-12, RS-485
Supply Voltage 12 to 24 VDC
Power Consumption 1.5 to 2 W max
Field of View (FOV) 3:1
Update Time 250ms
Emissivity Setting 0.9, Fixed
Spectral Response 5.5 to 20 μm
Ambient Temperature 0 to 70 ℃
Relative Humidity 95% non-condensing
Probe Dimensions 34.9 W × 94.3 H × 19.4 L mm
Probe Weight 230 g
Cable length between probe and signal conditioner 1 m
Cable length between signal conditioner and data logger 5 m (standard) | maximum: 10 m for voltage sensors; 50m for SDI-12; 200 m for 4 .. 20 mA and RS-485 sensors

 

canopy temperature and plant water potential
Canopy Infrared Temperature Water Potential

An example of the strong correlation between canopy temperature (Tc-Ta) and leaf water potential. (Image source: Gonzalez-Dugo et al, 2012, Fig.5)

A common application for the LT-IRM Canopy Temperature Sensor is to measure leaf, or plant, water potential. A large amount of scientific research has demonstrated that there is a direct, and strong, correlation between the temperature of a leaf/canopy and water potential (see example figure to the right). Therefore, the LT-IRM Canopy Temperature Sensor can be used to measure the water status of plants.

Canopy temperature increases and decreases throughout the day with ambient air temperature. A healthy canopy, with access to ample soil moisture, will have a high rate of transpiration which acts as a cooling effect. The process is similar to how humans sweat or perspire when we exercise to remain cool. A well irrigated and healthy plant will show a large temperature difference when compared with ambient air temperature. This is also known as the Leaf-to-Air, or Canopy-to-Air, Temperature Difference (also commonly expressed as Tc – Ta).

A plant under stress, particularly soil moisture stress, will show a lower Canopy-to-Air Temperature Difference. When soil moisture becomes limiting, the stomata on leaves begin to close which limits the rate of transpiration. Under this scenario, plants have a limited ability to cool the canopy via transpiration loss. In other words, plants are still exercising yet their perspiration has decreased. Therefore, the canopy temperature increases.

Scientific research has demonstrated that the increase in canopy temperature is directly related to the water status of the plant. As plant’s become less hydrated, or as leaf water potential becomes more negative, the Canopy-to-Air Temperature Difference also decreases.

Leaf to Air Temperature Difference

An example of how canopy temperature is related to ambient air temperature over a 24 hour cycle.

The close relationship between canopy temperature and leaf water potential has significant benefits for researchers and growers. Measuring leaf water potential, for example with a pressure chamber, can be time consuming and laborious. Sensors that can continuously measure leaf water potential, such as a psychrometer or Zim probe, are also unreliable, expensive and extremely fragile. The LT-IRM Canopy Temperature Sensor has advantages over these techniques because it is:

  • low cost
  • low maintenance
  • easy to install
  • and can connect to a data logger for continuous monitoring

Furthermore, Edaphic Scientific can install a LT-IRM system with an alarm or SMS alert. When canopy temperature becomes high, an alarm or alert is sent and growers can undertake management to decrease canopy temperature and prevent crop stress.