Abstract. In order to study the biochemical changes, increase of resistence to cold stress and possibility of reducing primary buds death of grape, an expriment was conducted in a factorial design based on randomized complete block design with three replications and two vines per plot in the city of Dena in 2014. The first factor was salicylic acid (SA) at concentrations of 0, 150, 300 and 450 mg/l, and the second factor was potassium sulphate (K2SO4) at the levels of 0, 1, and 2%. Sampling was performed after leaves drop and start of dormancy, endodormancy stage, and before the growth of buds in the following year, and the related characteristics were recorded in each stage. The results showed that different levels of SA, dates of sampling, interaction of SA and sampling date, interaction of SA and potassium sulphate, and interaction of potassium sulphate and sampling date had significant effect on Malondialdehyde at the level of 1%. Furthermore, Malondialdehyde was affected by interaction of SA and potassium sulphate, and interaction of potassium sulphate and sampling date at probability level of 5%. The results also showed that SA at different levels had significant effect on catalase enzyme at 1%. Interactions between SA and potassium sulphate, and between SA and sampling date caused a significant effect on the amount of peroxidase at 5 and 1% levels, respectively. Moreover, superoxide dismutase was affected significantly by sampling date and SA at the level of 5%.

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