Exogenous nitric oxide alleviates oxidative damage in turfgrasses under drought stress

• Exogenous nitric oxide increases the tolerance of turfgrasses under drought stress.
• The antioxidant enzymes' activity of turfgrasses is enhanced by NO donors.
• The maximum alleviation is obtained with the application of 200 μM SNP or PN.
• Warm season turfgrass C. dactylon has the highest activity for antioxidant enzymes.

Oxidative stress caused by drought stress is a major limiting factor for grass cultivation in arid and semi-arid regions. In order to investigate the effect of nitric oxide (NO) donors on drought tolerance and recovery of Poa pratensis L. ‘Balin’, Lolium perenne L. ‘Numan’ and Cynodon dactylon [L.] Pers., sodium nitroprusside (SNP) and potassium nitrite (PN) were applied at 150, 200 and 250 μM concentrations with irrigation intervals of 3, 5, 7 and 9 days. The NO donors significantly increased the antioxidant enzymes' activity of the three grass species during drought stress. This enhancing effect was not dependent on the source of NO (SNP or NP), but rather reliant on their concentrations. The maximum activity of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) was obtained with the application of 200 μM SNP or PN. Nitric oxide donors caused the greatest increase in activities of antioxidant enzymes in plants subjected to 7 or 9 days of drought stress. Among different turfgrasses tested under water stress, warm season turfgrass C. dactylon had the highest activity for antioxidant enzymes.