Thermography methods to assess stomatal behaviour in a dynamic environment.

Area of Science:

• Plant Physiology
• Remote Sensing
• Biophysical Modeling

Background:

• Thermography offers rapid, non-invasive plant measurements but struggles with deriving key physiological data like leaf transpiration (E) and stomatal conductance (gsw).
• Current methods often rely on stress indices derived from normalized leaf temperatures, which have limitations in dynamic environments.

Purpose of the Study:

• To present a simplified dynamic energy balance method for calculating 'wet' and 'dry' leaf temperatures.
• To enable accurate estimation of leaf transpiration (E) and stomatal conductance (gsw) from thermograms.
• To assess the spatial heterogeneity and rapidity of stomatal responses in wheat.

Main Methods:

• Solving dynamic energy balance equations to determine 'wet' and 'dry' leaf temperatures.
• Utilizing artificial leaf references with known conductance to overcome limitations of traditional stress indices.
• Applying pixel-wise calculations to thermograms for analyzing stomatal response rapidity.

Main Results:

• The developed method accurately estimates leaf transpiration (E) and stomatal conductance (gsw).
• Limitations of traditional stress indices in dynamic conditions were identified and addressed using artificial references.
• Spatial heterogeneity in stomatal behavior was revealed across wheat leaf laminae, showing 'patchy' responses.

Conclusions:

• The simplified energy balance approach enhances thermography's utility for plant water status assessment.
• Accurate E and gsw measurements are achievable, surpassing traditional stress index limitations.
• Understanding the spatial and temporal dynamics of stomatal conductance is crucial for water use efficiency.