Salicylic acid improves chilling tolerance by affecting antioxidant enzymes and osmoregulators in sacha inchi (Plukenetia volubilis)

The effects of pretreatment of 0–5 mM salicylic acid (SA) on the sacha inchi (Plukenetia volubilis) seedlings during chilling stress were investigated. The stress induced damage to seedlings, and SA pretreatment decreased the level of damage. Lipid peroxidation, measured in terms of malondialdehyde content, increased significantly by stress, and SA pretreatment prevented the increase because SA decreased the production rate of superoxide anion (O 2 ·― ) and H2O2 content. SA pretreatment increased the activities of antioxidant enzymes including superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase and decreased activity of dehydroascorbate reductase. In addition, SA pretreatment increased the content of proline and soluble sugar. Results suggested that the pretreatment of sacha inchi seedlings with SA may induce antioxidant enzymes which lead to increased chilling tolerance. The best protection appeared to be obtained from seedlings that were sprayed with SA at 0.5 and 1 mM. Induction of chilling tolerance in seedlings by exogenous application of SA may have a significant practical application in sacha inchi plantation.