SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/726375
www.stma.org October 2016 | SportsTurf 17 because when light strikes a chlorophyll molecule, it refl ects these colors at their respective range of wavelengths. This is why when we look at a turfgrass plant we see the color green. Refl ected light may be partially transmitted as well as it can be refl ected to other areas of the turfgrass canopy and transmitted there. Absorbed by the paint, light can provide heat, but is largely lost for photosynthesis. Turfgrasses use PAR to produce carbohydrates that provide energy and food storage compounds. The reaction that produces these carbohydrates is known as photosynthesis. For this light driven process to occur, plants exchange water vapor for carbon dioxide through transpiration. Photons of light excite chlorophyll molecules that are housed in the chloroplast of plants and as a result, initiate a chain of reactions that enable the turfgrass plant to capture carbon dioxide and convert it into usable forms of energy such as carbohydrates. RESEARCH TIME! Before our research it was not well known how paint colors would infl uence light refl ection, transmission, and absorbance. Our research indicated that lighter colors such as orange, yellow and white could transmit between 12 and 18% of available PAR while refl ecting 47 to 93%. Darker colors such as blue, green, maroon, purple, and black transmitted and refl ected much less (0 to 8%) while absorbing up to 95% of PAR. Our research found that much of the difference was due to the innate properties of the pigment color and part was due to the percent of solids by volume. So the formulation and color can impact light transmission. A good test of these transmission results was to measure total canopy photosynthesis. This would account for the high degree of refl ected light for a light-colored paint (e.g., white paint) that may still be used in photosynthesis despite a poor transmission percentage. As a percentage, leaves that were painted white maintained approximately 80% of the photosynthesis of the non-painted. Yellow and orange was about 70%; whereas red was about mid-50s. Purple and maroon were about 40%. Dark blue and black maintained less than 20% of the non-painted. So, the shading effect of paint by color turned out to be a very real and signifi cant limitation to the plant. As mentioned earlier, in addition to color, dilution can also play a role in total canopy photosynthesis. When comparing both white and red athletic paint (diluted and non-diluted) we found that the non-diluted formulation can have a profound effect. White and red non-diluted paint decreased total canopy photosynthesis by 25% more than when it was diluted using a 1 part paint:1 part water dilution. Red, non-diluted paint decreased total canopy photosynthesis by 75%. The reduction in pigment per unit area reduces the opacity so that more light can be transmitted to the chlorophyll. While this may be benefi cial to photosynthesis and plant health, diluting paint with water often reduces the brightness, coverage, longevity, and quality of paint applications. As a result, the need for brightness and uniformity must be balanced against the effects Field day demonstration of colors used in paint research using the Atlantic Coast Conference school colors. The relative influence of paint color on turfgrass photosynthesis.