Effects of Exogenous Sodium Nitroprusside on Drought Resistance of Creeping Bentgrass and Tall Fescue

Water deficit is a major limiting factor for turfgrass growth in arid and semi-arid regions. Thus, in this study the drought tolerance of two turfgrass species, creeping bentgrass (Agrostis stolonifera var. „Palustris‟) and tall fescue (Festuca arundinacea schreb var. „Ky 31‟) was investigated by sodium nitroprusside (material that release nitric oxide (NO)). A facrtorial experiment was carried out in completely randomized design with three replications. Three factors including; two turfgrass species, four levels of nitric oxide and four levels of drought stress. The results showed that drought stress and NO treatment had not significant effect on shoot length of both grass species. Drought stress significantly increased electrolyte leakage, but NO treatment reduced electrolyte leakage in drought stress conditions. In both turfgrass species, leaf relative water content decreased with increasing soil suction, but NO treatment maintained the leaf relative water content higher than untreated plants. In tall fescue NO significantly reduced peroxidase activity during drought stress when compared to the untreated plants, but in creeping bentgrass NO significantly increased activity of this enzyme. In both turfgrass species, superoxide dismutase activity of leaves decreased with increasing soil suction, however, different concentrations of NO significant increased the activity of this enzyme when compared to control. Finally, it appears that the nitric oxide by supresing free oxygen radicals and increasing antioxidant enzymes activity decreased electrolyte leakage and increased leaf relative water content, and as a result decreased drought stress damage in the turfgrasses.