The effect of sodium nitroprusside (nitric oxide donor) on enhancement of aged groundnut (Arachis hypogaea L.) seeds was investigated under drought stress. Seeds were primed in different solutions containing 0, 50, 100 or 150 µM sodium nitroprusside at 25 °C for 18 h and then subjected to 0, −0.4, −0.6, and −0.8 MPa drought stress for 10 d. Priming of aged seeds at different drought levels improved final germination percentage, germination rate, vigor index, seedling length, soluble sugars, total soluble proteins and the activities of antioxidant enzymes (catalase, superoxide dismutase, and ascorbate peroxidase) while mean germination time, electrical conductivity, malondialdehyde and hydrogen peroxide content decreased. Seed priming with 150 µM sodium nitroprusside at −0.8 MPa increased germination rate, seedling length, activity of catalase, superoxide dismutase and ascorbate peroxidase to 38.62%, 66.66%, 39.14%, 14.43%, and 42.51%, respectively. These results suggest that seed priming with sodium nitroprusside is effective in improving germination and seedling vigor of aged groundnut seeds through alleviating oxidative stress caused by drought stress.
