Release of temperature, GA₃ and ethylene to the dormancy of chinese narcissus (narcissus tazetta var. chinensis roem.)

Under natural condition, the respiration rate of the three-year-old bulbs of Chinese narcissus (Narcissu stazetta var. chinensis) declined from April to July, began rise and then declined again from late July to late August. The bud sprouting was postponed and sprouting rate was reduced by high temperature such as 30 °C. While, low temperature such as 15 °C was in favor of dormancy release. Continual low temperature treatment was needed for the bulbs dormancy breaking before late July, whereas shorter time was needed after that period. GA₃ had positive effects on the dormancy release of the bulbs only after late July. Certain concentration of ethylene treatment at any stage promoted the bud sprouting, which indicated ethylene is closed associated with the Chinese narcissus dormancy. The dormancy progression of Chinese narcissus could be divided into two stages-endormancy stage (before late July) and ecodormancy stage (after late July). The dormancy of ecodormancy stage is more easily broken by low temperature, GA₃ or ethylene.