Wooster, Ohio
February 26, 2009
When it comes to fresh vegetables
and fruits, color is one of the best indicators of quality.
Along with texture, size, and flavor, color plays an important
role in the business of horticultural crop production and
marketing.
In tomatoes, for example, color and color uniformity contribute
directly to quality and marketability. The presence of yellow
shoulder disorder, or YSD, a ripening disorder that results in
blotchy discoloration under the skin of the tomato, is a major
quality issue.
Color disorders are also an economic problem. U.S. Department of
Agriculture (USDA) "grades" are largely determined by the amount
of off-color tissue in products, and growers can receive
premiums for fruit based on color and uniformity. Discoloration
due to YSD also reduces concentrations of nutrients such as
lycopene and beta-carotene. Clearly, reducing YSD in tomatoes
could benefit producers, processors, and consumers alike.
In an issue of the Journal of the American Society of
Horticultural Science (ASHS) David Francis and his colleagues at
The Ohio State University's Agricultural Research and
Development Center and the College of Wooster describe the use
of a new tool they implemented in the Tomato Analyzer (TA)
software called Color Test (CT). This remarkable tool allows
scanning devices to be calibrated using color standards. The
objective of the research was to implement a new digital image
analysis tool.
According to the study, Tomato Analyzer was originally designed
to analyze the morphology of tomato fruit. The researchers in
this study developed a module for color measurement "to expand
the array of objective phenotypic analyses implemented". TACT
was applied to fruits and vegetables of various color and color
uniformity.
"TACT was designed to be user-friendly with minimum requirements
for running it, yet accurate and precise for collecting
objective measurements. It facilitates data collection and
management, and requires equipment that is relatively more
affordable", Francis explained.
Traditional tools used to measure color of vegetables and fruits
require extensive environmental control, especially for the
quality and quantity of light, shadow, and reflection. In
contrast, the flatbed scanners used in this study required only
a cardboard box as a cover to minimize the effect of shadow.
TACT was able to accurately capture and describe the
characteristic color for each crop when applied to other fruits
and vegetables of varying colors and color uniformity. Color
uniformity was also well characterized for fruit that tend to
have nonuniform pigmentation, such as strawberry. TACT proved to
be a reliable, precise, and affordable method for digital image
analysis of color
The study authors envision that TACT could be used not only in
color analysis of fresh crops, but perhaps to evaluate
discoloration of food after processing or cooking in food
science applications.
The complete study and abstract are available on the ASHS J.
Amer. Soc. Hort. Sci. electronic journal web site:
http://journal.ashspublications.org/cgi/content/abstract/133/4/579
Tomato
Analyzer-color Test: A New Tool for Efficient
Digital Phenotyping
Audrey Darrigues, Jack Hall, Esther van der Knaap
and David M. Francis
Department of Horticulture and Crop Science, The
Ohio State University, Ohio Agricultural Research
and Development Center, 1680 Madison Avenue,
Wooster, OH 44691
Nancy Dujmovic and Simon Gray
Department of Mathematics and Computer Science,
College of Wooster, 1189 Beall Avenue, Wooster, OH
44691
ABSTRACT
Measuring plant characteristics via image analysis
has the potential to increase the objectivity of
phenotypic evaluations, provides data amenable to
quantitative analysis, and is compatible with
databases that aim to combine phenotypic and
genotypic data. We describe a new tool, which is
implemented in the Tomato Analyzer (TA) software
application, called Color Test (TACT). This tool
allows for accurate quantification of color and
color uniformity, and allows scanning devices to be
calibrated using color standards. To test the
accuracy and precision of TACT, we measured internal
fruit color of tomato (Solanum lycopersicum L.) with
a colorimeter and from scanned images. We show high
correlations (r > 0.96) and linearity of L*, a*, and
b* values obtained with TACT and the colorimeter. We
estimated genotypic variances associated with color
parameters and show that the proportion of total
phenotypic variance attributed to genotype for color
and color uniformity measured with TACT was
significantly higher than estimates obtained from
the colorimeter. Genotypic variance nearly doubled
for all color and color uniformity traits when
collecting data with TACT. This digital phenotyping
technique can also be applied to the
characterization of color in other fruit and
vegetable crops. |
Founded in 1903, the American
Society for Horticultural Science (ASHS) is the largest
organization dedicated to advancing all facets of horticultural
research, education, and application. More information at
ashs.org |
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