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TURFGRASS SCIENCE

Response of Creeping Bentgrass Carotenoid Composition to High and Low Irradiance

Plant Sciences Dep., Univ. of Tennessee, 2431 Joe Johnson Dr., 252 Plant Science Bldg., Knoxville, TN 37996

^* Corresponding author (mcelroy{at}utk.edu)

Carotenoids are important photoprotectant and light-harvesting pigments within the photosynthetic apparatus. Little information is available regarding carotenoid physiology in creeping bentgrass (Agrostis stolonifera L.). Research was conducted to investigate relative high and low irradiance adaptation of creeping bentgrass with respect to ß-carotene and xanthophyll composition. ‘Crenshaw’ creeping bentgrass plants were acclimated for 7 d to relative high [47.9 mol m^–2 d^–1 photosynthetically active radation (PAR)] or low irradiance (4.7 mol m^–2 d^–1 PAR). After the acclimation period, plants were transferred from high to low (low irradiance treatment) and low to high (high irradiance treatment) irradiance. Clippings were harvested at 0, 24, 72, and 168 h after the acclimation period. Zeaxanthin and antheraxanthin decreased from 5.1 and 3.4 to 0.9 and 0.6 mg 100 g^–1 fresh weight (FW), respectively, over 168 h in low irradiance. As the turf adapted to low irradiance, violaxanthin, lutein, and lutein-5,6-epoxide (epoxylutein) increased at 24 h, but levels decreased from 24 to 168 h. Zeaxanthin and antheraxanthin increased in high irradiance, while violaxanthin and ß-carotene decreased. Lutein was the predominant carotenoid quantified regardless of irradiance treatment. Cumulative zeaxanthin, antheraxanthin, and violaxanthin increased as a percentage of the total carotenoids as the turfgrass adapted to high irradiance, but decreased in low irradiance. Conversely, neoxanthin and ß-carotene decreased in high irradiance and increased in low irradiance. Creeping bentgrass produces carotenoid amounts comparable to other plant species potentially attributable to selection efforts of more stress-tolerant varieties.

Abbreviations: ELU/LU ratio, epoxylutein to lutein ratio • FW, fresh weight • HPLC, high performance liquid chromatography • LHC, light harvesting complex • NPQ, nonphotochemical quenching • PAR, photosythetically active radiation • ZA/ZAV ratio, zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin ratio