Abstract: [Objective] Respiration intensity is closely related to cold resistance of plants, and temperature is an important factor affecting respiration.On the basis of preliminary identification of the cold resistance, this study explored changing trends of relevant physiological indexes during dormancy of different cold-resistant hazel hybrids, and physiological mechanisms to adapt to the low-temperature environment, to provide abasis forfurther studyingcold resistance of hybrid hazels.[Method] The phenology of three clones (84-349, 84-237 and 84-572) with different coldresistance, which were selected in our previous experiments, were observed.We measured respiration rate, branches electrolyte leakage, and soluble protein content and soluble sugarscontentsof shoots of the three clones during dormancy, to explore the relationship between dormancy and cold resistance.[Result] The strong cold resistance clone, 84-349, was the earliest to enter the dormant period and the latest to bloom;There were no differences in physiological indexes during the deep dormancy over the three clones. However, in the early stage and late stage of dormancy, the clone of 84-349 had the lowest respiration rate, the least electrolyte leakageand the highest soluble sugar and soluble protein contents.Whereas the weak cold resistance clone, 84-572, was opposite, with thehighest electrolyte leakage, highest respiration, and the lowest soluble sugar and soluble protein contentsamong the three clones.[Conclusion] Three hybrid hazelnut clones with different cold resistance had different physiological performancesin dormancy.Compared with the weak cold resistance clones, thestrong cold resistancecloneresisted low temperatureby early entering dormancy, reducing respiration rate, lowering the electrolyte leakage and increasing storage ofenergy matter indormancy.

Key words: hazelnut hybrid, cold resistance, dormancy