Effects of hydrogen cyanamide on physiological changes during endodormancy releasing and flowering of sweet cherries in warm region

Abstract

A trial was conducted to verify the effect of hydrogen cyanamide (HC) application on endodormancy release and blooming of 'Summit' sweet cherry trees, as well as on carbohydrates, nitrogen content, and endogenous hormone. The use of HC hastened bud release, shortened the bloom period that resulted in improved fruit set. Moreover, the HC-treatment also led to a quick hydrolysis of starch. The increase in the contents of glucose, fructose and total nitrogen, and the decrease of sucrose and sorbitol contents were coincided with the process of endodormancy release and flowering when HC was applied to 'Summit' sweet cherry. In addition, gibberellic acids (GAs) might have selective effects in the process of endodormancy release and blooming. A higher GAs/ABA ratio was observed in HC-treated 'Summit' branches from endodormancy release until full bloom. As for indole-3-acetic acid (IAA) and cytokinins, the contents of IAA, Zeatin (ZT), Dihydrozeatin (DZ) and N(6) -(Δ(2) -isopentenyl) adenosine (2-ip) increased gradually during the processes of endodormancy release in 'Summit' sweet cherry trees. For IAA/ABA ratio, it also showed an increasing trend in this process. The results of this study confirmed that IAA, and cytokinins also play a certain role in promoting dormancy release of perennial plants, and the use of HC promoted the increase in IAA and cytokinins content.