11/13/2023 - By JJ Jansen

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As we move away from the summer solstice, our daylight length interval becomes shorter, and the light quality and intensity are dramatically reduced, leading to reduced photosynthetic activity (PA) in plants. This begs the question, what can turf managers do to maximize PA and carbohydrate production before the onset of plant dormancy? The following 2011 publication by Harell’s Director of Agronomy, Dr. Raymond Snyder, sheds some light on this question and more about Photosynthetically Active Radiation.

What is PAR® SG?

Some think it is just a simple colorant to enhance the aesthetic color of the playing surface, while others think Harrell's SprayMAX® PAR® SG relates to a golf acronym. The letters “PAR” actually stand for “Photosynthetically Active Radiation.”

What is PAR® SG on a Plant Physiology Level?

PAR is the amount of light a plant has available for photosynthesis. The chlorophyll within the plant utilizes available light in the 400 to 700-nanometer wavelength range, see illustration. Several external factors can reduce the amount of PAR available to plants, this may include anything that reduces the amount or quality of sunlight. Seasonal changes are primarily the largest component, affecting light angle and the photoperiod interval. Some secondary regulators may be cloud cover, shading by trees, and buildings. Air pollution has also been documented to affect PAR by filtering out the amount of sunlight that can reach plants.

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How is PAR® SG Useful? And why is it Important?

By applying consistent applications of Harrell’s PAR® SG, you are in essence reducing the severity of harmful UV and infrared wavelengths. So, in essence, what PAR® SG is providing the plant is a selective light filter by reducing UV-b and UV-a, allowing the transmission of blue to red wavelengths into the plant (Snyder, 2011). These blue-to-red wavelengths are the key to a plant's photosynthesis, by providing the correct light spectrum to the plant and reducing UV-b and UV-a, you achieve increased turf quality and color.

How does PAR® SG Aid in Plant Health?

Many turf managers remove PAR® SG applications from their spray rotation as summer ends and we transition into the shadier fall and winter months. But, by adding PAR® SG to your overall, year-round nutritional program, you are potentially providing the plant with greater opportunities to build root mass and achieve maximum plant health throughout the growing season. Potentially increasing carbohydrate production to help overcome any abiotic stresses the winter months may present.

Note for applications, depending upon the desired color intensity and your frequency of spray interval, apply Harrell's PAR® SG at 8 to 16 oz. per acre.

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Your Harrell’s Rep Can Help You with Your PAR® SG Application

If you have any questions on Harrell'sSprayMAX® PAR® SG, what rates you should apply, or how it works further, please reach out to your local Harrell's Representative. They are your best resource for application planning and making the most out of Harrell’s products, like PAR® SG.

References:

Snyder, R. 2011. Investigation of UV Blocking Pigments and Known UV Protectants. PHD Laboratory, Davie, FL.