A Whole Leaf Comparative Study of Stomatal Conductance Models

Area of Science:

• Plant Physiology
• Biophysics
• Computational Biology

Background:

• Stomatal conductance regulates gas exchange critical for photosynthesis and transpiration.
• Previous models often assumed uniform stomatal responses across the leaf surface.
• Understanding spatial variation in stomatal function is key to plant adaptation and productivity.

Purpose of the Study:

• To investigate the spatial operation of three stomatal conductance models on a whole leaf scale.
• To analyze how local mechanical processes influence leaf-level physiological activities.
• To assess the impact of environmental factors on spatially distributed stomatal responses.

Main Methods:

• Development and application of a detailed whole leaf hydraulic model.
• Simulation of three distinct stomatal conductance models.
• Quantification of leaf-area distributions for photosynthesis, transpiration, stomatal conductance, and turgor pressure.
• Analysis of model responses to varying CO2 concentration, relative humidity, and light irradiance.

Main Results:

• A mechanical stomatal conductance model predicts spatial variation in photosynthesis and transpiration, even under uniform environmental conditions.
• Hydraulic pressure gradients, driven by guard and epidermal cell turgor, lead to non-uniform physiological activity.
• Non-linear relationships between stomatal aperture and cell turgor result in more complex spatial patterns and environmental dependencies.

Conclusions:

• Leaf physiological functions like photosynthesis and transpiration are not uniformly distributed.
• Mechanical stomatal models provide a more realistic representation of spatial variations in leaf function.
• Further experimental validation is needed to quantify these spatial distributions in living leaves.