Dormancy Period of Winter Bud of Idesia Polycarpa and Its Physiological and Biochemical Characteristics

In order to investigate the dormancy process of Idesia polycarpa winter buds and its physiological and biochemical characteristics, we observed the sprouting growth of 1-year-old branches of I. polycarpa from Tokyo povenance winter buds and the content and activity of physiological and biochemical substances through hydroponically dormant branches at 25°C during different periods of time, including soluble sugar, soluble protein, catalase(CAT), peroxidase(POD), superoxide dismutase(SOD), auxin(IAA), abscisic acid(ABA) and trans changes of content or activity of zeatin(tZR) and gibberellin(GA₃). The results showed that under the climatic conditions in Zhengzhou, the dormancy introduction period for the I. polycarpa buds in September-October, the deep dormancy period in November, the dormancy release period in December-February, and the inner growth period in March. In the dormancy process of I. polycarpa winter buds, the contents of soluble sugar and soluble protein accumulated from the dormancy introduction stage to the deep dormancy stage, and reached the maximum at the deep dormancy stage. The content of soluble sugar was significantly higher at the late stage of deep dormancy than at other stages, then began to decline, and the soluble protein content rapidly decreased after entering the deep dormancy period, and then the soluble protein content increased first, then decreased, and then increased with the release of dormancy; the activity of antioxidant enzymes POD and CAT showed a 'decreasing-rising' trend. The activity of POD was significantly lower when entering the deep dormancy period, while the activity of CAT was significantly lower than that of other stages; the content of endogenous hormones IAA and ABA showed an upward trend from a lower level during the dormancy introduction period of I. Polycarpa winter buds. When entering the deep dormancy period, the content was significantly higher than other stages, and then decreased. The content of GA₃ and tZR were significantly higher than that of other stages during the deep dormancy period and the late ingrowth period. The content of GA₃ and tZR began to decline after reaching a high level during the deep dormancy period, and then began to increase after reaching a minimum on December 15. With the decrease of temperature, the relative content of ABA in I. polycarpa winter buds gradually increased, which promoted the dormancy of winter buds. With the deepening of dormancy, the antioxidant capacity of winter buds gradually decreased. The relative contents of GA₃ and tZR increased gradually in dormancy release period, which accelerated the process of dormancy release. With the release of dormancy, the antioxidant capacity of winter buds was improved.