Effect of warm and cold stratification, and ethanol treatment on germination of Corylopsis seeds

Seed germination experiments with Corylopsis coreana, C. sinensis var. calvescens, and Corylopsis gotoana were conducted. Corylopsis coreana seeds were treated at 5, 7.5, 10, 12.5 and 20 degrees C to study the upper temperature limit to break dormancy. Seeds of C. sinensis var. calvescens were treated 1 month with warm stratification (WS) at 10, 15, 20, and 25 degrees C followed by cold stratification (CS) at 5 degrees C for 0, 1, 2, and 3 months to understand the requirements of WS and CS to effectively break dormancy. Germination of Corylopsis seeds at 15-20 degrees C without CS suggests that dormancy is considered shallow and the upper temperature limit to break is 12.5 degrees C. Immersing seeds in water or ethanol induced seed germination which may result from leaching of inhibitors from the seed. Observation of seed coats following treatment with water and ethanol by means of low temperature scanning electron microscopy (LT-SEM) revealed elongated and rectangular/hexagonal shaped cells in C. coreana and irregular jigsaw puzzle-piece shapes in C. gotoana. In conclusion, dormancy in Corylopsis is considered shallow and the optimum CS is suggested to be 7.5 degrees C, while the optimum WS is ranging from 12.5 to 20 degrees C.