ISSN 1021-4437, Russian Journal of Plant Physiology, 2006, Vol. 53, No. 1, pp. 126–133. © MAIK “Nauka /Interperiodica” (Russia), 2006.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 139–147.
For many living organisms, coloration and color
pattern are important features for survivability in
nature. Plants contain a wide variety of pigments such
as carotenoids, chlorophylls, anthocyanins, and beta-
lains. However, functions of color in plants are not yet
fully understood [1, 2]. As chemical compounds, the
pigments are often involved in biochemical reactions.
Anthocyanin pigments are known to contribute to pro-
tection against oxidative stresses [3, 4] and strong light
intensity including UV-B [5, 6], suggesting indispens-
able roles of color in plant physiology. The tropical
, cv. Golden Leaves, is a mutant
showing yellow leaves that contain low amounts of
photosynthetic pigments. The alteration of leaf coloration
is attributed to changes in photosynthetic activity . Two
families of the Caryophyllales are known to possess
betalains instead of anthocyanins; the latter have been
completely replaced by betalains in metabolism .
Such differences in the pigments are thought to be in
concordance with the phylogenetic relationship within
the Caryophyllales . Therefore, from the standpoint
of phylogeny or taxonomy, coloration or color pattern
recognition is one of the important factors to distin-
guish species. These color features are also needed for
camouﬂage (e.g., possible undermining protecting
color of predators ), and to fascinate animals (e.g.,
ﬂower color for pollination) in breeding strategies .
However, objective handling of coloration to examine
phenotypes or to study physiological and/or ecological
implications of plants with color patterns includes dif-
ﬁculties because there is a considerable perception gap
for visualization of color among people.
The tropical tree croton
colorful ornamental plant. Croton contains a huge num-
ber of cultivars with phenotypically diverse leaves hav-
ing various color patterns of variegation, which are
composed of green, red, and yellow colors. Thus, anal-
ysis and typing for coloration and color pattern are very
difﬁcult. At present, there is no convenient method of
typing suitable for characterizing the leaves.
In food sciences, methods and protocols for color
measurement have been well-developed . An image
fusion approach to extract color features has also been
tested for fruit quality assessment . Methods
applied for screening crops are also available. However,
these methods are based on complex algorithms, which
are optimized for speciﬁc plant materials and purposes
and required specialized instruments. Therefore, con-
venient methods are needed to measure the colors of an
object’s image without specialized instruments.
A Simple Method for Two-Dimensional Color Analyses
of Plant Leaves
H. Shimoji*, G. Tokuda**, Y. Tanaka*, B. Moshiri**
***, and H. Yamasaki**
*Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Okinawa 903–0213, Japan
**Center of Molecular Biosciences, University of the Ryukyus, Okinawa 903–0213, Japan;
***Faculty of Engineering, University of Tehran, 14395/515, Tehran, Iran
Received July 8, 2005
—Coloration and color pattern are basic information for plant physiology, ecology, and taxonomy.
Until recently, such color analysis of biological materials required expensive equipment. Here we report a con-
venient method for analyzing color of plant leaves with ImageJ, free software. Color digital images of croton
leaves were divided with ImageJ into Red, Green, and Blue images, and then exported as two-dimensional
numeric data. After processing images with Adobe Photoshop Elements and Microsoft Excel, color patterns
were obtained as histograms. A comparison of the histograms evaluated characteristics of croton leaf variega-
tion. The method successfully quantiﬁed color information of the plant leaves with an inexpensive PC set. Apart
from taxonomic applications, the simple algorithms allow application of the present methodology to various
types of color and color pattern analyses.
Key words: Codiaeum variegatum - color measurement - digital image analysis - ImageJ - color pattern rec-
: B—blue; G—green; R—red.
The text was submitted by the authors in English.