athletic field managers maintain trimmed turfgrass with great
precision, carefully painting crisp lines and colorful logos on their
grass before each game. While these fields appear to be in perfect
health, some field managers have noted deteriorating turfgrass beneath
repeated paint applications.
research now suggests why. In a study that appears in the
September-October issue of Crop Science, three North Carolina State
University researchers found that grasses coated with latex paints show a
notable reduction in photosynthesis.
their study, which was funded by the Center for Turfgrass Research and
Environmental Education at NC State University, the researchers prepared
60 pots with sand and peat substrate before seeding each with perennial
ryegrass, a grass commonly used on professional football and baseball
fields including most NFL and MLB fields. After the grass matured, two
different dilutions (no-dilution, and 1:1 dilution with water) of red
and white latex paints were applied to the turf samples weekly for six
recognize how paint affects turfgrass health, it’s important to first
understand how paint itself functions. Latex paints consist of four
different components: resins, solvents, additives, and pigments. Each
has a unique role in the painting process.
act like an adhesive, allowing paint to stick to surfaces. Solvents
dilute the paint and help ensure a consistent application thickness.
Additives help distribute the pigments, the fourth component, into the
liquid paint. Of these ingredients, the scientists say pigments pose the
biggest threat to turfgrass.
are used in paint to ensure a surface is completely coated, and give
paint its color by absorbing specific wavelengths of light while
reflecting others. This wavelength-selective absorption allows for the
wide variety of paint colors that exist today.
the NC State researchers suspected the coating of pigment on turfgrass
was also damaging the grass by shielding it from the sun and reducing
photosynthetically active radiation (PAR). PAR consists of wavelengths
of light in the 400 to 700 nm range that plants use in photosynthesis.
researchers looked at the reflection, transmission, and absorption of
PAR in the four different paints, determining that red paint absorbs the
highest amounts of PAR. By observing the carbon exchange rates in the
painted turfgrass samples, the team also found red paint was more
damaging to total canopy photosynthesis (TCP) than white paint, although
diluting each color with water reduces their negative effects.
from this study further suggest that white paint reflects more PAR in
the turfgrass canopy, allowing it to be absorbed by plants for
photosynthesis. Over the course of the six-week study, diluted white
paint reduced TCP by only 19%. However, the absorption of PAR by red
paint eliminates the benefits of PAR reflection by the white and reduces
TCP more drastically, the effects worsening as paint applications
increase. The no-dilution red paint produced a 75% reduction in TCP by
the final application.
results from this study confirmed pigment’s crucial role in the
availability of PAR for plant use underneath latex paint. But more
research is needed to fully explore the impacts different types of
athletic field paint have on turfgrass photosynthesis and growth, say
a global sports market where field paint application plays a crucial
role in the industry, understanding the delicate relationship between
latex paints and grass will not only help improve turfgrass health but
may also change the properties of paint products themselves.
Source: Crop Society of America