Canopy chlorophyll fluorescence applied to stress detection using an easy-to-build micro-lidar

Area of Science:

• Plant physiology
• Remote sensing technology
• Agricultural science

Background:

• Vegetation fluorescence is a key indicator of plant health and stress.
• Existing methods for measuring fluorescence, like Sun-Induced chlorophyll Fluorescence (SIF), have limitations in data consistency and environmental dependency.
• Accurate and reliable fluorescence measurements are crucial for precision agriculture and ecological monitoring.

Purpose of the Study:

• To introduce and validate LEDFLEX, a micro-lidar system for precise vegetation fluorescence measurement.
• To demonstrate LEDFLEX's capability in detecting water stress signatures in various crops.
• To highlight LEDFLEX's potential to improve the interpretation of passive fluorescence measurements.

Main Methods:

• LEDFLEX utilizes blue Light-Emitting Diodes (LEDs) for canopy illumination and synchronized detection to measure fluorescence and reflectance.
• The system acquires data simultaneously, including photosynthetic active radiation and air temperature, with a footprint of approximately 1 m² at 8 m distance.
• Field experiments were conducted on pea, mint, and sweet potato canopies under varying watering conditions.

Main Results:

• LEDFLEX successfully identified distinct water stress signatures in pea canopies, characterized by changes in fluorescence levels (Fs and Fmin).
• Similar water stress patterns were observed in mint and sweet potato canopies, confirming the system's broad applicability.
• The micro-lidar provided robust fluorescence yield data due to consistent excitation intensity and fixed geometry.

Conclusions:

• LEDFLEX offers a reliable method for active fluorescence measurements, overcoming limitations of passive methods.
• The technology can accurately assess vegetation water status and potentially other physiological stresses.
• Integrating LEDFLEX with SIF measurements promises enhanced understanding of plant responses to environmental conditions.