Athletic Field Paint Impacts Transpiration and Canopy Temperature in Bermudagrass.

Athletic field paints have varying impacts on turfgrass health which have been linked to their ability to alter photosynthetically active radiation (PAR) and photosynthesis based on color. It was further hypothesized they may also alter transpiration and canopy temperature by disrupting gas exchange at the leaf surface. Growth chamber experiments evaluated the effects of air temperature and six colors of paint on daily water loss and canopy temperature in ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy]. Daily water loss and canopy temperature were measured every 24 h using gravimetric techniques and an infrared digital thermometer, while lab experiments examined the thickness of white and black paint on the leaf surface. In non-painted bermudagrass canopies, daily water loss increased (P ≤ 0.0001) with canopy temperature from 29 to 36^oC while in painted bermudagrass canopies it decreased (P ≤ 0.0001) as canopy temperature increased from 29 to 40^oC.  Yellow and white paint impacted transpiration and canopy temperature the least, while black and blue caused the greatest reductions in transpiration and highest increases in canopy temperature. Cross-sections of painted Tifway indicate paint may limit evaporative cooling by clogging stomata. Increased absorption of radiant energy by paint coupled with limited evaporative cooling result in increased heat stress and decreased turfgrass performance in painted canopies.