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Updated: Jul 11, 2025
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Evaluation of Photosynthetic Behaviors by Simultaneous Measurements of Leaf Reflectance and Chlorophyll Fluorescence Analyses
Published on: August 9, 2019
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Tracking canopy chlorophyll fluorescence with a low-cost light emitting diode platform
Logan E G Brissette1, Christopher Y S Wong1, Devin P McHugh1
1Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA.
Aob PLANTS
|November 8, 2023
Summary
A new low-cost photodiode system effectively measures canopy-scale LED-induced chlorophyll fluorescence (LEDIF) at night. This method tracks plant photosynthetic activity changes, showing potential for drought monitoring and broader ecological studies.
Area of Science:
- Plant physiology
- Remote sensing
- Ecology
Background:
- Chlorophyll fluorescence is a key indicator of plant photosynthetic activity.
- Remote sensing of fluorescence (SIF) offers canopy- and satellite-scale insights but requires expensive, high-spectral-resolution instruments.
- Measuring steady-state chlorophyll fluorescence at the canopy level under natural light is challenging.
Purpose of the Study:
- To develop and validate a novel, low-cost photodiode system for measuring LED-induced chlorophyll fluorescence (LEDIF) at the canopy scale.
- To assess the potential of this night-time active remote sensing method to track changes in photosynthetic activity during drought stress.
- To compare the performance of the photodiode system with a hyperspectral spectroradiometer for LEDIF retrieval.
Main Methods:
- A low-cost photodiode system was designed to measure far-red chlorophyll fluorescence emission induced by a blue light-emitting diode (LED) source at night.
- LEDIF was retrieved from a broadleaf evergreen shrub (Polygala myrtifolia) under imposed drought conditions.
- Measurements were validated against a hyperspectral spectroradiometer, and correlated with stomatal conductance, vegetation indices (PRI, NDVI), and PAM fluorometry data.
Main Results:
- The photodiode system demonstrated strong agreement with hyperspectral measurements for LEDIF retrieval (R² = 0.77).
- LEDIF measurements closely tracked drought-induced decreases in photochemical quenching (R² = 0.69), Fv/Fm (R² = 0.59), and the photochemical reflectance index (PRI) (R² = 0.59).
- The system successfully monitored changes in canopy-scale photosynthetic activity during drought.
Conclusions:
- The low-cost, night-time photodiode method for measuring LEDIF is a viable and cost-effective alternative to traditional methods.
- This approach shows significant potential for monitoring plant photosynthetic status at scales larger than individual leaves over time.
- The LEDIF photodiode system can serve as a meaningful indicator of physiological drought response and photosynthetic activity.
