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TURFGRASS SCIENCE

Antioxidant Metabolism Associated with Summer Leaf Senescence and Turf Quality Decline for Creeping Bentgrass

Dep. of Plant Biology and Pathology, Rutgers Univ., New Brunswick, NJ 08901

^* Corresponding author (huang{at}aesop.rutgers.edu).

Turf quality of creeping bentgrass [Agrostis stolonifera var. palustris (Huds.) Farw.] often declines during summer months. Whether summer bentgrass decline is associated with oxidative stress is unclear. The objectives of this study were to investigate seasonal changes of antioxidant activities and lipid peroxidation under different mowing heights for two creeping bentgrass cultivars (L-93 and Penncross) differing in heat tolerance and to determine whether such changes could be associated with turf quality decline during summer. Penncross and L-93 were grown under USGA-specification putting green conditions at the Turfgrass Research Center at Manhattan, KS, in 1999 and 2000. Turf was mowed every day at 3 mm or 4 mm. Turf quality, leaf chlorophyll (CHL), and protein content declined while electrolyte leakage (EL) and lipid peroxidation increased from May to July through September for both cultivars at both mowing heights. Activities of superoxide dismutase (SOD), catalase (CAT), hydrogen peroxidase (POD), and ascorbate peroxidase (APX) increased from May to July when temperatures increased from optimum (<20°C) to moderate level (26°C), then declined to the lowest level in August when temperature reached the highest level (>30°C), and recovered by October. Similar seasonal patterns of antioxidant activities were observed for both cultivars and mowing heights. In conclusion, summer bentgrass decline was related to the decline in antioxidant activities and lipid peroxidation. Both cultivars were able to acclimate to increasing temperatures by increasing the activities of antioxidant enzymes to scavenge active oxygen species in the early summer, but lost the scavenging ability by midsummer.

Abbreviations: APX, ascorbate peroxidase • CAT, catalase • CHL, chlorophyll • EDTA, ethylenediaminetetraacetic acid • EL, electrolyte leakage • MDA, malondialdehyde • NBT, nitroblue tetrazolium • POD, hydrogen peroxidase • SOD, superoxide dismutase