四种台湾林木种子之层积与激勃素处理

Stratification and Gibberellin Treatments for Seeds of Four Taiwan residents Tree Species

台湾所产的珊瑚树、杨梅、山樱花和刺叶桂樱等种子已知皆具有休眠性，珊瑚树种子需要先以5℃低温层积才能发芽，而杨梅、山樱花和刺粟桂樱等种子则需要暖低温组合层积处理。本研究利用激勃素GA3刺激这四种林木种子的发芽，探讨激勃素层积和休眠解除问之相关性。激勃素GA3无法刺激珊瑚树新鲜种子的发芽，然而新鲜种子先以5℃低温层积4星期，再用GA3处理则可发芽。因此推测先予短暂的低温层积可增加种子内微量的内在激勃素浓度，再结合外在激勃素处理即可促进发芽。刺叶桂樱新鲜种子仅用GA3处理无怯发芽，需要先以30/20℃变温8星期以上，在不经低温层积处理下再用GA3处理即可发芽，其原因可能与种子内胚的未完全成熟和硬实内果皮的纾解有关。杨梅和山樱花新鲜种子可以直接用GA3处理，取代暖低温组合层积处理而发芽，推测可能这类种子对激勃素GA3作用较爲敏感，或种子内虽已含有一些激勃素，但浓度尚不足以促进发芽。

Freshly harvested seeds of the native trees, Viburnum odoratissimum, Prunus spinulosa, Myrica rubra and Frunus campanulata, are dormant. The dormant seeds of V. odoratissimum were released by 5℃ cold stratification, while seeds of the other 3 species were released by warm plus cold stratification. The effect of gibberellin A3 (GA3) on the germination of the seeds of the seeds of the 4 trees was studied, and the relationships among GA3, cold stratification, and dormancy released of seeds are discussed. GA3 could not replace cold stratification for germination of V. odoratissimum seeds which required 5℃ stratification for 4 wk prior to GA3 application; it is speculated that partial cold stratification increases the small amount of endogenous gibberellin which combines with the exogenous GA3 to produce germination. Fresh seeds of P. spinulosa also failed to germinate by GA3 alone and required alternating temperatures of 30/20℃ for at least 8 wk, and then GA3 could replace cold stratification for germination. The alternating temperature requirement for P. spinulosa seed is probably related to after-ripening of the underdeveloped embryos and released of the hard endocarp. Applied GA3 was capable of replacing warm plus cold stratification and stimulating fresh seed germination in M rubra and P. campanulata; it is speculated that the seeds might be sensitive to GA3, or the seeds contain some active endogenous gibberellins in the embryo but the amount is insufficient to enhance fresh seed germination by itself.