Researchers applied Kubelka-Munk stack layer theory for absorbing/reflecting materials to quantify spectra of the Chilean Bellflower. Researchers used Avantes.com spectrometers and equipment.

1. Research Notes: Kubelka-Munk
Absorbing Layer Stack Theory
Applying the Kubelka-Munk Absorbing Layer Stack Theory to
Flower Coloration of the Chilean Bellflower, Nolana Paradoxa

2. Introduction
Researchers from the
University of Groningen,
Netherlands are uniting the
disciplines of biology and
physics in the quantitative
analysis of the reflectance
spectra of flowers.
This has important
implications for:
● Field of evolutionary biology
● Understanding the relationship
between plants and pollinators
● Understanding of optical properties
of pigmentation and light scattering
● Add to body of reference spectra
data
● Industries such as thin film,
coatings, dyes, and paints.

3. Flower Petal Anatomy
The petals of a flower are
made up of several layers
consisting of outer
epidermal layers and inner
pigmented and light
scattering layers of the
mesophyll.

4. Flower Anatomy (cont)
Pigment layers selectively
absorb incident light within a
specific wavelength, while
light scattering structures
and vacuoles backscatter
the incident light in all
directions, giving the flower
its color.

5. Measuring the Colorization of Flowers
Dr. Doekle G. Stavenga
studied the Chilean
bellflower which has
distinct color
differentiation between
the upper and lower
surface

6. Geometrical Optics for Flower Color
The interaction of light within a
plant to produce flower color
used to be measured and
explained by geometrical optics.
However, plant structures are
homogeneous, which makes
optical analysis inconvenient.

7. Kubelka-Munk Theory
Theory Outcomes:
-Absorption and scattering coefficients to be
derived from measured transmission and
reflectance spectra
-Stravenga and Van Der Kooi used this method on
a non-invasive method for estimating chlorophyll
content.

8. Stacked Layer Theory
-Used to describe flower coloration
Applies Kubelka-Munk Theory
-This method uses combined stack
reflectance and transmission spectra to
estimate the reflectance and transmission
spectra for each layer

9. Avantes Spectrophometric Measurement
Researchers employed the following
Avantes Spectrometers:
-(AvaLight-D(H)-S) to deliver light via
optical fiber to an integrating sphere
(AvaSphere-50-Refl).
-AvaSpec-ULS2048XL-USB2 Used to
capture the reflected light by a second
optical fiber.
Stavenga and van der Kooi then
interpreted this measured
transmission and reflectance spectra
for the corolla using the Kubelka-
Munk absorbing stack layer model

10. Conclusion and Continuing Research
-Casper van der Kooi and Doekele Stavenga has
greatly advanced our understanding of how
plants use light.
-Competition for pollinators affects the spectral
display of flowers
-This research into the efficacy of the Kubelka-
Munk method can have potentially wide-reaching
impact on both the study of plants with potential
agricultural applications, as well as potential
relevance to other applications which concern
stack metrology.