Microtensiometers to measure continuous water potential in woody crops

Interested in plant water relations, but you have no time for taking pressure chamber measurements, or dealing with challenging instruments that need replacing every other week?

The FloraPulse microtensiometer is a set-and-forget sensor of water potential initially developed at Cornell University. After a 15-minute installation, our system gives you continuous readings of plant water potential for multiple years. Receive continuous pressure chamber data, on your phone, without manual measurements in the field! With access to season-long, continuous water potential measurement, new research avenues become possible.
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Why FloraPulse for your experiments

  • Realtime, continuous water potential data
  • Can last 2+ years installed in the same tree
  • Easy 20-minute installation
  • Validated in many crops
  • Stop the pressure bombing hassle
  • Eliminate safety hazards with high pressure in Scholander chamber
  • Receive the data automatically online with easy download
  • New sensor, new data, new research, new discoveries.

How it works

The FloraPulse system involves a microchip tensiometer that is embedded inside the tree woody tissue and directly measures the tree water potential. This microtensiometer has a measurement range of up to 100 bars of tension, a feat made possible by the use of nanoporous silicon membrane. The membrane pores are around 2nm in diameter–very small indeed.

We have spent over 10 years refining the design of the sensor and installation method to ensure accurate measurement in a variety of crops. Our system uses a combination of physical and chemical barriers to eliminate issues with the plant wounding response, and to keep the sensor working for years without maintenance.

FloraPulse enables new research

Getting 24/7, realtime SWP allows for completely new research. With realtime data, you can see the small fluctuations in water potential during the day; how the crop responds to irrigation, cloudy skies or temperature changes; how water potential behaves during the night and even changes in water potential during plant dormancy in the winter.

Why FloraPulse is superior to other methods

Pressure chamber
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Stem psychrometry
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Pressure chamber readings are the current gold standard to determine plant water status. Unfortunately the measurements often depend on the operator (i.e. different users get different results) and the high pressure instrument is a safety hazard. The logistics of the pressure chamber are also painful, and require visiting remote fields with a heavy instrument to take measurements during the hottest part of the day. With these drawbacks, most research can maybe get one measurement a week of uncertain accuracy. You need accurate, automated measurements.
Stem psychrometers have existed for many years now and are a well-known tool to measure stem water potential in a variety of crops. The instrument has a well-understood mechanism of measurement, and can provide accurate measurements when installed and handled correctly. Unfortunately, this instrument is fragile and requires experienced hands for correct installation. Even when installed correctly, the instrument will usually fail after days to weeks due to intrusion of the plant exudates into the measurement chamber, or loss of contact of the thermocouple pair. The instrument further requires expensive electronic equipment to read the microvolt signals.You need an instrument that is accurate for the long run.
Stem osmometry
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A stem osmometer has been recently introduced to measure and manage plant water status. This measurement instrument has similarities with the FloraPulse microtensiometer, in that both instruments use exchange of fluids to equilibrate the fluid pressure between the xylem tissue and the sensor, and use a pressure sensor to measure this pressure. Unfortunately, the larger size of theosmometer and the osmotic membrane create problems with the measurement. The osmometer’s larger fluid reservoir and its slower osmotic membrane means that the measured water potential is always
4-5 hours behind the tree water potential –thus, you only get a dampened average of the tree water potential, not the actual measurement. Furthermore, this instrument is very sensitive to temperature fluctuations, which cause large spikes in measurement during the hottest parts of the day
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Soil moisture
Soil moisture sensors only tell you half the story by only measuring the water content in a small volume of soil. You are making critical decisions based off incomplete data. The soil may appear wet when the tree is thirsty, or the soil may appear dry when the tree is waterlogged. You need to ask the tree directly.
Evapotranspiration
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Dendrometer
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Evapotranspiration (ET) tells you how much water the trees have used, approximately, based on assumptions of leaf cover and measurements taken on a grass field. Even with accurate ET data, common unknowns can completely throw off your results: underground water sources, accumulated water from winter precipitation, incorrect assumptions in your crop coefficient. Unfortunately, guidelines for ET were developed 40 years ago with completely different irrigation systems and methods. ET, although a useful measure, cannot guide irrigation timing.
Dendrometers have been around for a long time and are robust instruments. They measure the expansion and contraction of the trunk over the course of the day and use this data to estimate the tree water status. This measurement is unfortunately indirect and depends on a calibration between trunk expansion and water potential, a calibration that varies from crop to crop, year to year, and location to location. Dendrometers thus can be a great research tool, but require extensive calibration and verification of the data. The ideal instrument can measure water potential directly, without calibration.
Sap flow
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Sap flow meters measure the flux of water through the plant vascular system (xylem), which is difficult to interpret because there is no 'gold standard'. Each tree will have different sap flow readings depending on its own particular trunk structure and this unfortunately means that sap flow needs to be calibrated for each individual plant. In other words, two trees with the same sap flow measurement could have wildly different water status.
FloraPulse
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The FloraPulse microtensiometer gives you direct measurements of tree water potential, 24/7 every day. Our instrument combines the advantages of the pressure chamber (accurate measurement), without the drawbacks of manual measurement. Our sensors have been developed over 10+ years to work with a variety of crops and provide accurate, realtime measurement of stem water potential.Ask the tree directly if it needs water, and get the most accurate water status data, without the hassle.

Validated in many crops

  • Almond
  • Grape
  • Pistachio
  • Orange
  • Prune
  • Apple
  • Pear
  • Peach
  • Apricot
  • Plums
  • Cherry
  • Olive
  • Mango
  • Ask us about your crop!
Below you can see data from our field trial in a Napa Valley Cabernet field. The sensors have been accurately measuring SWP for over two years and counting. We show the continuous SWP data, the midday SWP data (the lowest value for each day, around 2pm) and the predawn SWP data (the highest value for each day, around 6am).

Midday Stem Water Potential

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24/7 Stem Water Potential

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Predawn Stem Water Potential

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Specifications

  • Water potential range: 0 to -35 bar
  • Resolution: 0.1 bar
  • Accuracy: ±5% of reading

Scientifically Validated

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“Other companies use different approaches to monitor plant waterstress, but FloraPulse technology gives the most accurate picture”

- Professor Ken Shackel, irrigation expert, UC Davis

Professor Ken Shackel, UC Davis

Available in 3 versions

All systems include the microtensiometer probes, and tools needed for installation. Installation is easy and takes 20 minutes, just follow our instructional video
Analog probe
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  • Compatible with scientific dataloggers
SDI-12 probe
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  • Compatible with any SDI-12 compliant datalogger
All-inclusive annual subscription
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FloraPulse subscription.Includes sensor probe, installation kit, cellular data and visualization
  • Includes probes, 4G datalogger, cellular data and visualization platform. This is a plug and play system to get you running in 30 minutes. Install the sensor, hang the logger and you’re good to go.
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Installation tools included.
Microtensiometer probe with 10' extension cord. Available in analog and SDI12 version.
Continuous SWP data from almond tree. Shown in the FloraPulse online dashboard.
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Midday SWP data from almond tree, shown in the FloraPulse online dashboard. The figure shows the measured midday SWP (black line), manual pressure bomb measurements (stars), the SWP baseline calculated from weather data (blue line), the color-coded stress levels (colored bars) and the recommended stress level (grey shading).