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

IntroductionResearchers 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.

Flower Petal AnatomyThe 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.

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.

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

Geometrical Optics for Flower ColorThe 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.

Kubelka-Munk TheoryTheory 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.

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

Avantes Spectrophometric MeasurementResearchers 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

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.