Abstract:

The effects of exogenous salicylic acid(SA) (5 and 10 mmol·L^-1)on activities of antioxidant enzymes in seedlings of Fraxinus mandshurica were analyzed in the present paper.Activities of superoxide dismutase(SOD) were decreased by SA,and reduced with the increase of SA concentrations,resulting in the increase of superoxide radicals.The activities of catalase(CAT) and ascorbate peroxidase(APX) were inhibited by SA,and their activities reduced with the increase of SA concentrations.Although the activities of peroxidase(POD)increased,H₂O₂ levels increased in leaves with SA treatment because of the inhibition of CAT and APX.The activities of glutathione reductase(GR) was decreased by SA,and reduced with the increase of SA concentration. In general,malondialdehyde(MDA) levels in leaves with 5 mmol·L^-1SA treatment were 35.19% lower than that of control,suggesting low concentration of SA reduced freezing injury in seedlings of Fraxinus mandshurica.

Key words: Freezing stress, Salicylic acid, Antioxidant enzymes, Fraxinus mandshurica