Abstract: By applying exogenous NO or depleting endogenous NO, this paper studied the regulation effect of NO on the leaf antioxidation system of tall fescue (Festuca arundinacea) cultivars Arid3 and Houndog5 in hydroponic culture under high light stress. Comparing with the control, the endogenous NO production under high light stress in Arid3 leaves was increased by 201.5%, while that in Houndog5 leaves was only increased by 21.1%. Houndog5 leaves were more liable in suffering oxidative damage than Arid3 leaves, with the electrolyte leakage and MDA content increased by 72.6% and 85.1%, and 36.1% and 30.1%, respectively. Pretreatment with 0.2 mmol·L^-1of NO eliminator 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) obviously aggravated the oxidative damage to Arid3 and Houdog5, while supplementing with 0.1 mmol·L^-1 of NO donor sodium nitroprusside (SNP) alleviated the high light induced electrolyte leakage and malondiadehyde (MDA) and H₂ O₂ contents in both Arid3 and Houndog5 leaves. The production of superoxide (O₂^X) was reduced, the activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) were increased, and the lipoxygenase (LOX) activity was decreased. The effect of SNP was reverted when a NOspecial scavenger PTIO was added. It was suggested that NO could effectively protect Arid3 and Houndog5 leaves from oxidative stress by increasing the activities of ROS-scavenging enzymes under high light stress.

Key words: Urban eco-engineering, Plants species selection, Comprehensive evaluation, Indices system, Classification of evaluation