Abstract: A sand culture experiment was conducted to study the effects of nitric oxide (NO) donor sodium nitroprusside (SNP) on the growth, leaf active oxygen metabolism, and leaf osmotica accumulation of ryegrass (Lolium perenne L.) seedlings under aHCO₃ stress. Under the stress of 100 mmol NaHCO₃·L^-1, applying 60 μmol·L^-1 of SNP could alleviate the seedling’s growth inhibition, increase the leaf O₂^-· generation rate and H₂O₂ and malondialdehyde contents, promote the leaf superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, and plasma membrane H⁺-ATPase activities, increase the leaf lutathione, soluble sugar, soluble protein, and proline contents and K⁺/Na⁺ ratio, and decrease the leaf catalase activity and ascorbic acid content. Little effects were observed on the leaf free amino content. These results suggested that SNP could alleviate the damage of alkali stress on Lolium perenne eedling leaves via activating the antioxidant system activity, promoting the osmotica accumulation, and improving the Na⁺ and K⁺ balance, and accordingly, promote the alkali resistance of the ryegrass plant.

Key words: Heavy metal contaminated soil, Physio-chemical technique, Phytoremediation