木蘭科烏心石與華蓋木種子發芽休眠之研究

木蘭科烏心石與華蓋木種子有休眠性，苗圃播種後發芽率低，且發芽不一致。本研究目的確定此二樹種種子發芽所需條件，提供有效的方法生產種苗。採自台灣中部出雲山和烏石坑新鮮的烏心石種子，在變溫25/15、20/10、15/5℃及光照下發芽率80~90%最高，其他較高溫度如30/20、30/15℃和定溫25℃的發芽率都較低。然而，採自中國雲南的華蓋木種子除了15/5℃外，其他上述五種溫度之發芽率都在30~40%，沒有顯著差異。解剖種子發現，烏心石與華蓋木種子胚都很小，胚根突破種皮之前，胚在種子內生長，當長度分別增加至2.5和2.6倍時發芽，因此胚生長快慢反應種子的發芽速度。烏心石種子開始發芽時間是在播種後3~4星期，且溫度影響發芽，由此判斷具有形態生理的休眠。低溫5℃層積處理8~12星期或激勃素處理都能促進烏心石種子的發芽。總結是烏心石種子有淺度簡單級的形態生理休眠。華蓋木種子在4星期內發芽完畢，因此只有形態的休眠，沒有生理的休眠。烏心石種子乾燥至含水率9.0%或更低，可儲藏在5、-20和-196℃至少3年，因此烏心石種子的儲藏性質為正儲型。建議烏心石種子播種前先用5℃層積處理8~12週，以加速發芽。

關鍵字

低溫層積處理；激勃素；烏心石；形態生理休眠；華蓋木

並列摘要

Seeds of Michelia compressa and Pachylarnax sinica of the Magnoliaceae exhibit dormancy. Poor germination and non-uniform emergence of seeds in the nursery were found after sowing. Thus, the aim of this study was to determine the germination requirements of seeds of the 2 species in order to provide an effective protocol to produce plants. Up to 80~90% of fresh seeds of M. compressa harvested from Chuyunshan and Wushikeng germinated at alternating temperatures of 25/15, 20/10, and 15/5℃ in light, and other high temperatures such as 30/20, 30/15℃ and constant temperature at 25℃ had low germination percentages. However, up to 30~40% of seeds of P. sinica germinated at the above 5 temperatures in light except for 15/5℃, and germination percentages among the incubation temperatures did not significantly differ. Embryos of the 2 studied species were small, and they had to grow 2.5~2.6-fold before radical emergence. The speed of embryo growth responded to the germination speed. Seeds of M. compressa began to germinate in 3~4 wk, and temperature affected seed germination; thus, they exhibited morphophysiological dormancy. Further, cold stratification at 5℃ for 8~12 wk and gibberellic acid treatment enhanced Michelia seed germination. Thus, the seed population exhibited non-deep simple morphophysiological dormancy. Seeds of P. sinica germinated completely within 4 wk, thus, they exhibited only morphological dormancy. Seeds of M. compressa with a moisture content of ≤ 9.0% stored at 5 or -20℃ and in liquid nitrogen retained their germinability for at least 3 yr, indicating that they had orthodox storage behavior. Cold stratification of seeds of M. compressa at 5℃ for 8~12 wk is recommended to increase the germination speed and produce uniform seedlings.

並列關鍵字

cold stratification ； gibberellic acid ； Michelia compressa ； morphophysiological dormancy ； Pachylarnax sinica

國際替代計量

木蘭科烏心石與華蓋木種子發芽休眠之研究

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