Influence of Surface Structure, Pigmentation and Particulate Matter on Plant Reflectance and Fluorescence

Area of Science:

• Plant physiology
• Biophysics
• Optical spectroscopy

Background:

• Plant leaf optical properties are crucial for assessing physiological status and stress.
• Variations in leaf morphology and pigmentation can complicate optical measurements.
• Understanding these variations is key to accurate remote sensing and plant health monitoring.

Purpose of the Study:

• To investigate how leaf variegation, pigment composition, and surface features affect photophysical behavior.
• To evaluate the applicability of established optical models (Pile of Plates, Kubelka-Munk) to diverse leaf types.
• To explore the relationship between optical parameters, pigment concentration, and water content in non-standard leaves.

Main Methods:

• Analysis of four distinct leaf types: green, purple, hairy, and variegated.
• Scanning electron microscopy for foliar surface morphology.
• UV-vis and near-IR reflectance/transmittance spectroscopy.
• Calculation of absorption (k) and scattering (s) coefficients.
• Fluorescence spectroscopy with correction for re-absorption.

Main Results:

• Established optical models (Pile of Plates, Kubelka-Munk) remain valid for non-standard leaves.
• Common spectral indices are unreliable for water content prediction in atypical leaves.
• The direct proportionality between absorption and pigment concentration is lost in hairy leaves.
• Leaf surface morphology and pigmentation influence optical features and susceptibility to particulate matter effects.

Conclusions:

• Leaf surface morphology and pigmentation significantly impact leaf optical properties.
• Simplified models are needed to accurately interpret optical data from diverse leaf types.
• These findings have implications for understanding plant-environment interactions and photosynthesis under stress.