Evaluation the effect of soybean oil on some physiological parameters related to cold tolerance in table grape cultivar "Bidaneh Sefid"

Coating the vine is one of the common methods for increasing tolerance of vines against temperature changes and oils are one of the cheapest cover. For physiological study of soybean oil coating effect on table grape buds, spraying was done with concentration of 0, 5% and 10 % on grape cv. "Bidaneh sefid", in a randomized complete block design on early fall and late winter 2012 in three replications (blocks) and six plants for each replicate. Sampling was done in three different times (January, February and March) during the winter and twice (3-4 leaf stage of buds and early stage of blooming) in the spring of 2013. Results showed that coating the vines with soybean oil in winter, had a positive effect on the vines only in march, and with increase in the amount of soluble carbohydrates, the electrolyte leakage of buds was decreased in comparison with the control. In spring, treatment with of 5% soybean oil increased proline amount and reduced the amount of malondialdehyde showing the positive effects of this concentration on preserving membrane under low temperatures. But 5% soybean oil had negative effects on photosynthesis pigments. During spring, treatment with 10% soybean oil increased the amounts of soluble carbohydrates, protein and enzymes of peroxidase, ascorbate peroxidase and polyphenol oxidase. As a result, soybean oil coating is not suitable for winter. Using 5% concentration to delay flowering buds in spring and escape from the spring frost is suitable but is necessary to be used with other fertilizers for increasing pigments and improve the yield at the beginning of bud growth and for decreasing negative effects of oil on photosynthesis pigments.