What is sap flow technology? 

  • All plants have sap moving through internal tubes and conduits. Like blood in humans, sap contains water, nutrients, solutes and hormones, and is vital to the healthy functioning of plant tissues and cells. 

  • Sap flow technology refers to the tools and methods involved in sensing the movement of sap through a plant [as well as the insights that this provides into plant health].

  • Sap flow technology principally uses heat as a tracer of water movement through the plant.

How is sap flow technology being used?

  • By sensing/detecting the movement of sap, sap flow sensors are able to quantify how much water the plant is moving, as well as to provide an indication of the health of a plant.

  • The scale can vary - we can detect the movement of water into a small tissue, like an individual fruit (e.g., apple) or through a main branch or trunk of a tree. 

  • With implications for understanding fruit quality, yield, or irrigation scheduling.

How does it work?

  • Sap flow is detected using several different methods, all of which rely upon the general practise of using heat as a proxy for the movement of sap. 

  • Our sensors rely upon the heat ratio method, which is where a heat pulse is applied to a stem and temperature sensors detect its movement either side of the heating element. 

  • In doing so we are able to quantify the rate of sap movement. 

  • Careful calibration of our products allow us to reveal the volume of sap moving through the plant.

What information does sap flow technology tell me?

  • Sap flow can reveal how rapidly sap is moving through different tissues. 

  • Sap flow can reveal the volume of sap moving through different tissues or into a fruit etc.

  • Health of the plant…the rate of water flow out of a plant is proportional to the amount of carbon assimilation (uptake of CO2). Like using heart rate to evaluate how active a person is. Other analogies? 

  • Quantify how healthy trees are…like using sleep monitors to detect how healthy a lifestyle is.

What are the benefits of sap flow technology?

  • Improved knowledge of (overall) plant function and health. 

  • Precise understanding of water movement within tissues, to gain insight into fruit expansion, quality etc.

  • Fine tune irrigation and water scheduling based on the function of the plant

o Why is sap flow monitoring better than soil moisture monitoring?

  • Direct monitoring of the plant allows users to evaluate the health of the plant directly.

  • Soil moisture cannot provide insights into fruits or individual tissues etc.

  • Soil moisture is one step removed from the plant. 

  • Expense? 

And what about drones?

  • Drones monitor evapotranspiration by looking at the spectral emissions from the plant and/or the leaf temperature.

  • Unable to quantify individual tissues (e.g., apples). 

  • Drones are not continuous.

  • Something about the calibration (onerous)

  • Unproven - uncertain what the numbers mean

  • Drones cannot fly under certain conditions; under mesh netting or in windy conditions.  

Will the devices damage my plants?

  • Our external devices can be placed directly on the outside of the bark, thereby avoiding damage to the internal plant tissues. 

  • Our sensitive temperature sensors are pads that obviate the need for needles that puncture the xylem. This allows us to monitor sap movement without disrupting its movement or inducing a wounding effect.   

Where can I find research on the benefits of sap flow?

  • Our team of research scientists have published widely on the use of sap flow in natural plants and agricultural crops. Please contact us for a list of sap-flow related lirature.

How can sap flow technology aid in Water resource management?

  • Sap flow technology allows for an extremely accurate calculation of water usage across all types of plants. Plant Pulse’s digital solution can aggregate water usage by species and by individual user in an area that’s sharing water resources. This allows for an in-depth understanding of water consumption trends and gives management teams the information they need to manage their resources.

  • Potential benefits: Precision water consumption monitoring, ability to hold individual users in an area accountable for their water consumption, auditing of recorded water consumption

How can sap flow technology aid in Agriculture and farming?

  • Sap flow technology puts the health of a plant directly in your hands. It gives a precise understanding of the health of your crop, and allows you to optimise the use of water, fertiliser and other resources, while giving farmers the information they need to consistently improve yield and quality.

  • Potential benefits: Decreased water consumption, increased yield, improved crop quality, precise health monitoring, decreased diesel and electricity spend

How can sap flow technology aid Trade / industry bodies?

  • Large organisations are increasingly held responsible for ensuring the sustainability of their produce and their end-to-end supply chain. Sap flow technology gives unparalleled confidence that scarce resources are being closely monitored and managed, and provides the information necessary to have confidence that sustainable growing practices are being deployed. Our solution puts this information at your fingertips so that certifications are supported by meaningful effort to reduce water usage in the growing process.

  • Potential benefits: Decreased water consumption, increased yield, improved crop quality, precise health monitoring, decreased diesel and electricity spend [can be repeated from above]

How can sap flow technology aid Ecology and conservation?

  • Sap flow technology gives extreme insight into the health of almost any plant species. This gives previously-inaccessible information to ecologists so that data-backed decisions can be made on how to protect and preserve our precious natural resources. Plant Pulse’s solution gives you real-time visibility of plant stressors in even the remotest of environments, helping you best serve our natural resources.

How can sap flow technology aid Research?

  • Sap flow technology provides unparalleled information on plant health and function. Plant Pulse’s sensors provide information that is 3-4x more granular than other scientific apparatus available, at a fraction of the cost. Not to mention the ability to view the plant’s health in real-time.

What does your solution comprise?

  • The Plant Pulse sap flow sensor kit comprises the sensor unit (which is attached to the plant), the lora basestation (which uploads collected data to the cloud), and the online dashboard (where the user is able  to login and monitor the plants in real time).

How many sensors will I need?

  • The number of sensors required depends entirely on the application. In the case of agricultural applications, we would recommend at least 6-10 sensors per hectare (depending on topography) while, for scientific studies, the density will depend entirely upon the nature of the research and number of species being studied.

Where is the best place to install the sensors?

  • It is recommended that the sensor head be attached to the distal end of the branches/leaves, the younger the branch the better (so as to maximise heat transfer). The logger unit, which is attached to the sensor head via a cable, can be securely mounted to the tree trunk at lower level or at another convenient location.

How long does installation take?

  • When completed by our professional team, installation can take as little as 10 minutes per sensor head. For agricultural applications, we would recommend at least two days to complete a farm installation.

Can I install my own sensors?

  • At this stage, considering the need to ensure correct attachment of the sensor head, it is recommended that the Plant Pulse team of technicians carry out all installations. The only exception to this is for scientific applications, where careful instructions will be sent to the researchers involved to ensure that the equipment is installed correctly.

How many base stations will I need?

  • For most applications, you will require only one base station. This station will collect and transmit the data of any number of sensors located within farm/study boundary.

How is my information protected?

  • All data collected by our devices is automatically encrypted and transmitted to the cloud in this format. The data is then de-encrypted on our servers and displayed correctly on our dashboard.

How frequently do the sensors upload data to the cloud?

  • Sap flow measurements are taken every 15 minutes and uploaded to the cloud. In the event of signal or power loss, the data is stored on location up until the signal is restored and can be uploaded once more.

Are you limited to certain countries?

  • While our technical team is currently located in South Africa, we are able to ship devices to any country of your choice and will be expanding our technical capacity to a number of other countries in the years to come.

How long do the batteries last?

  • At present, our rechargeable Li-ion batteries last upwards of 7-9 months.

What if a sensor breaks?

  • Depending on the nature of the problem, we may need to send a technician out to resolve problems of a technical nature. Should you have problems with a broken sensor, please contact our support team for further assistance.

Is there a warranty on the sensors?

  • The sensors come with a 12-month warranty.