Lou Ann McKnight1, Jeffrey Beasley1, and Edward Bush2. (1) 226 J.C. Miller Hall, Louisiana State University AgCenter, Louisiana State University, School of Plant, Environmental and Soil Sciences, Baton Rouge, LA 70803, (2) 257 J.C. Miller Hall, Louisiana State University AgCenter, Louisiana State University, School of Plant, Environmental and Soil Sciences, Baton Rouge, LA 70803
Elevated ozone levels in urbanized areas of the United States
are not only harmful to humans but pose a significant threat to urban
landscapes. In cities such as Baton Rouge, Louisiana,
ozone levels commonly exceed attainment standards set by the EPA. Even though ozone continues to rise in many
urbanized areas, very little is known regarding turfgrass tolerance to ozone toxicity. Two commonly grown warm-season turfgrasses, centipedegrass (Eremochloa ophiuroides)
and St. Augustinegrass (Stenotaphrum secundatum) were exposed to acute ozone
toxicity (200 ppb) using specially designed chambers. Plants were exposed to ozone for 4 hours a
day for a total of 8 hours over 2 days. At
the end of the second day, plants were visually rated for injury and
photosynthetic fluorescence measurements were collected. Centipedegrass
showed no visual symptoms or changes in photosynthetic fluorescence. Conversely, St. Augustinegrass
exhibited mottling and necrosis on leaf tissue as well as reduced photosynthetic
fluorescence. Symptoms from St. Augustinegrass were similar to symptoms of St. Augustinegrass infected with
the panicum mosaic virus. Based on these findings, centipedegrass
has greater tolerance of acute, high concentration ozone exposure compared to
St. Augustinegrass.