Wednesday, November 15, 2006 - 9:00 AM
259-3
Evaluation of Bentgrass Carotenoid Composition Under High and Low Irradiance.
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 adaptability of creeping bentgrass with respect to β-carotene and xanthophyll composition. ‘Crenshaw’ creeping bentgrass plants were acclimated for seven days to relative high or low irradiance. After acclimation period, plants were transferred from high to low irradiance (low irradiance adaptability) and low to high irradiance (high radiance adaptability). Clippings were harvested at 0, 24, 72, and 168 h after acclimation period. Zeaxanthin and antheraxanthin decreased from 3.4 and 2.4 to 0.7 and 0.5 mg/100 g fresh weight (FW), respectively, over 168 h in low irradiance adaptability. Violaxanthin increased from 2.3 to 4.0 mg/100 g FW in 24 h in low irradiance adaptability, but levels decreased over 168 h. Zeaxanthin, antheraxanthin, and all other carotenoids increased in high irradiance adaptability. Lutein was the predominant carotenoid quantified regardless of irradiance adaptability. Cumulative zeaxanthin, antheraxanthin, and violaxanthin increased as a percentage of the total carotenoids in high irradiance adaptability, but decreased in low irradiance adaptability. Conversely, neoxanthin and β-carotene decreased in high irradiance adaptability and increased in low irradiance adaptability. Creeping bentgrass produces carotenoid amounts comparable to other plant species. However, unsustainable violaxanthin potentially contributes to the relative intolerance of creeping bentgrass to shade conditions.
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