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Our scientific foundation

The technology behind Phyto-IT and TreeWatch.net is based on more than 15 years of research at Ghent University (Lab of Plant Ecology, Prof. Kathy Steppe). Below you will find a thematic overview of the key peer-reviewed publications that underpin our platform.

Thema 01

Dendrometers — stem diameter as water status indicator

Stem diameter variations as a versatile research tool in ecophysiology

De Swaef T., De Schepper V., Vandegehuchte M.W., Steppe K. (2015)

Tree Physiology, 35(10), 1047–1061

Micrometre-precise measurements of stem diameter reveal much more than mere growth: the subtle shrinkage and swelling of the stem tell day by day how well the plant is hydrated, how much water it has in reserve and when it experiences stress. For growers and fruit growers, this means one compact dendrometer sensor becomes both a drought stress warning system and a growth monitor. You steer irrigation based on what the plant itself 'says', rather than solely on soil or climate models.

Read full paper →Free access via publisher

Diel growth dynamics in tree stems: linking anatomy and ecophysiology

Steppe K., Sterck F., Deslauriers A. (2015)

Trends in Plant Science, 20(6), 335–343

Trees and plants grow mainly at night — and this study scientifically explains why. The authors show that turgor-driven cell expansion is limited to the night because daytime transpiration lowers water potential below the threshold for cell wall stretching. Our sensors reveal that nocturnal growth window that would otherwise remain invisible. Growers get a fairer picture of real growth performance and can fine-tune climate and irrigation strategies to the natural rhythm of the plant.

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Thema 02

Sap flow sensors

Sap-flux density measurement methods: working principles and applicability

Vandegehuchte M.W., Steppe K. (2013)

Functional Plant Biology, 40(3), 213–223

Not all sap flow sensors are equal. This review — with over 350 citations the most cited methodological sap flow review of the past decade — compares the main measurement methods (Heat Ratio, Heat Field Deformation, Granier/TDP, Heat Pulse) and clearly explains which technique works best for low, high or even reversed sap flow. This is the technical basis on which we base our sensor choice: we don't just choose a method — we choose the right method for your crop.

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A comparison of sap flux density using thermal dissipation, heat pulse velocity and heat field deformation methods

Steppe K., De Pauw D.J.W., Doody T.M., Teskey R.O. (2010)

Agricultural and Forest Meteorology, 150(7–8), 1046–1056

In a direct field comparison, this research shows that the classic Granier method (thermal dissipation) systematically underestimates actual sap flow: TDP values were on average 44% lower than Heat Field Deformation values, with the largest deviations at high sap flow densities. A wrong sensor choice can therefore lead to almost half the measurement error — and thus to wrong irrigation or forest management decisions. Investing in a high-quality sap flow sensor pays for itself quickly in water, energy and yield.

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Thema 03

Mechanistic RC model & Tree Water Potential

★ Fundament

A mathematical model linking tree sap flow dynamics to daily stem diameter fluctuations and radial stem growth

Steppe K., De Pauw D.J.W., Lemeur R., Vanrolleghem P.A. (2006)

Tree Physiology, 26(3), 257–273

This is the founding paper behind the 'Steppe model' — the mechanistic framework that links sap flow, stem diameter and growth in one mathematical model. Raw sensor data only gains real value when a model converts it into interpretable parameters such as turgor, water potential and growth rate. This foundation distinguishes Phyto-IT from pure data loggers: we don't sell sensors, we sell insight. The scientific foundation of everything we do.

Read full paper →Open Access

Development and verification of a water and sugar transport model using measured stem diameter variations

De Schepper V., Steppe K. (2010)

Journal of Experimental Botany, 61(8), 2083–2099

This follow-up research also brings sugar transport into the Steppe model: not only water, but also the flow of carbohydrates through the phloem is included. For sectors where sugar content matters — fruit, grapes, tomatoes — this opens doors to sensor-driven quality management, not just quantity. Our technology sees not only whether your plant has water, but also whether the sugars are reaching the fruits smoothly. A strong USP for premium crops and quality differentiation.

Read full paper →Open Access
Thema 04

TreeWatch.net & Phyto-IT — plants speak

★ Hero Paper

TreeWatch.net: a water and carbon monitoring and modeling network to assess instant tree hydraulics and carbon status

Steppe K., von der Crone J.S., De Pauw D.J.W. (2016)

Frontiers in Plant Science, 7, 993

This is the paper that scientifically frames the concept of 'plants speaking via the internet'. It describes how the TreeWatch.net platform combines sensors (sap flow + dendrometer) with the Steppe model to let trees literally 'tweet' their water and carbon status in real time. Not science fiction, but a validated platform published in Frontiers in Plant Science. The scientific foundation of the entire Phyto-IT story.

Read full paper →Open Access

Direct uptake of canopy rainwater causes turgor-driven growth spurts in the mangrove Avicennia marina

Steppe K., Vandegehuchte M.W., Van de Wal B.A.E., et al. (2018)

Tree Physiology, 38(7), 979–991

This research shows that mangrove leaves directly absorb rainwater through the leaf, immediately causing a growth spurt in the stem. It is the first direct dendrometer-based evidence that foliar water uptake triggers turgor recovery in the wood tissue of a field-grown mangrove — earlier isotope studies could only infer the effect indirectly. Our sensors enable discoveries that no other measuring instrument can reveal.

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Sap flow as a key trait in the understanding of plant hydraulic functioning

Steppe K., Vandegehuchte M.W., Tognetti R., Mencuccini M. (2015)

Tree Physiology, 35(4), 341–345 (editorial)

A short, powerful opinion piece in which Steppe and top colleagues state that sap flow is the key parameter for understanding the hydraulic functioning of plants. Sap flow technology is not a gadget, but a core measurement of modern plant science. A reference that places the importance of what we measure at the highest scientific authority.

Read full paper →Open Access
Thema 05

Applications — Tomato & protected horticulture

Linking stem diameter variations to sap flow, turgor and water potential in tomato

De Swaef T., Steppe K. (2010)

Functional Plant Biology, 37(5), 429–438

In this study the Steppe model is successfully applied to tomato plants for the first time. The authors show that the stem diameter of a tomato — measured with a simple dendrometer — is a reliable indicator of turgor, sap flow and water potential. For greenhouse growers, this is the scientific backbone of precision irrigation: one sensor per plant can suffice to fine-tune water application millimetre by millimetre to the plant's needs. Your plant tells you when it is thirsty — we translate that signal into a watering moment.

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Tomato sap flow, stem and fruit growth in relation to water availability in rockwool growing medium

De Swaef T., Verbist K., Cornelis W., Steppe K. (2012)

Plant and Soil, 350(1–2), 237–252

In tomatoes on rockwool, the authors showed that a modest drop in substrate moisture content from about 80% to 55% caused fruit growth to fall back 38%, while stem diameter increase fell by only 12% and sap flow by only 9% — the fruit is thus the most sensitive 'stress meter' of the plant. Do not rely solely on classic stock measurements, as the yield loss has already begun before the plant visibly suffers. Sap and stem sensors detect this much earlier and protect against loss of quality and kilograms.

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All publications are the property of the respective publishers and authors. Phyto-IT only refers to official sources. For access to publications behind a paywall: contact the Lab of Plant Ecology, Ghent University.