Determination of resistance to low temperatures of winter buds on lateral shoot present in Karaerik (Vitis vinifera L.) grape cultivar

This study aims to determine the low temperature resistance of dormant buds at nodes with or without lateral shoots of Karaerik grape cultivar, and explain the relationship between the resistance and biochemical parameters in this grape cultivar. In this study, the mean values of high temperature exotherms (HTEs), low temperature exotherms (LTEs), water, reducing sugar, total soluble protein contents and antioxidant enzyme activities of dormant buds taken from nodes with or without lateral shoots were determined. The experiment has been found that buds in nodes with lateral shoots showed HTE and LTE at higher temperatures (HTE average -6.7 degrees C and LTE average -8.3 degrees C) than buds (HTE average -7.9 degrees C and LTE average -11.5 degrees C) in nodes without lateral shoots; therefore, buds in nodes with lateral shoots had less tolerance to low temperature. Additionally, lower sugar (average 41.05 mg g(-1)), protein (average 1.61 mg g(-1)), superoxide dismutase (average 425.27 EU g(-1) tissue), peroxidase (average 2516.1 EU g(-1) tissue) and polyphenol oxidase (average 7283.1 EU g(-1) tissue) were determined for buds taken from nodes with lateral shoots. Due to the fact that dormant buds taken from nodes with lateral shoots decreased the resistance to low temperatures, this research suggests that these lateral shoots should be excised with the summer pruning at the regions, where low temperatures caused the damages.