Abstract. Askari grape is the dominant cultivar of the region which is damaged annually by winter cold. To study the biochemical changes and to reduce the effect of cold stress during the winter, this study was conducted in one of the vineyards of Dana city as a factorial experiment with a randomized complete block design with three replications and two vines in each plot. In this experiment, salicylic acid at concentrations of 0, 150, 300 and 450 mg/l and potassium sulphate at 0, 1, and 2% were used as foliar spray in 2014. Sampling was performed at different periods: two weeks after spraying, the onset of dormancy, deep dormancy stage and before bud growth in the following year, and related characteristics was measured and recorded in each stage. Sampling stages had significant effect on the increase of soluble sugars at 1%, while the interaction of salicylic acid × stages of sampling, and salicylic acid × potassium sulphate × stages of sampling had significant effect at 5%, and other treatments had no significant effect on soluble sugar content. Sampling stages had significant effect on the starch of grape bud at 1%, and other treatments had no significant effect on the starch. The effects of sampling stages and the interaction of potassium sulphate × stages of sampling on the protein content of grape buds were significant at the levels of 1% and 5%, respectively, and other treatments did not show significant effect on the protein content. The proline content of grape buds was significantly affected by salicylic acid at 5%, as well as the stages of sampling, the interaction of salicylic acid × potassium sulphate, salicylic acid × stages of sampling, potassium sulphate × stages of sampling and salicylic acid × potassium sulphate × stages of sampling at the level of 1%, and other treatments had no significant effect on proline content. Increase in the amount of salicylic acid and potassium sulphate and their interaction caused a significant effect on the increase in the amount of soluble sugars, protein and proline of buds, however, their effect on the starch was not significant.

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