入侵種夏威夷型銀合歡與臺灣5種原生植物的種子發芽溫度及耐旱能力

SEED GERMINATION TEMPERATURE AND DESICCATION TOLERANCE OF INVASIVE HAWAIIAN LEUCAENA LEUCOCEPHALA AND FIVE TAIWANESE PLANTS

劉恩妤(En-U Liu)；簡慶德(Ching-Te Chien)；劉瓊霦(Chiung-Pin Liu)

發芽特性 ； 夏威夷型銀合歡 ； 族群擴張 ； 種子耐旱性 ； Germination-related features ； Leucaena leucocephala ； Population colonization ； Seed tolerance to dessication

中華林學季刊

51卷1期（2018 / 03 / 01）

37 - 52

繁體中文

本研究比較入侵種夏威夷型銀合歡(Leucaena leucocephala)與5種臺灣原生樹種，相思樹(Acacia confusa)、茄苳(Bischofia javanica)、草海桐(Scaevola taccada)、水黃皮(Pongamia pinnata)和欖仁(Terminalia catappa)種子在不同溫度的發芽表現，及夏威夷型銀合歡和相思樹種子在不同發芽階段的耐旱能力，藉以探討夏威夷型銀合歡族群在臺灣擴展的優勢性。夏威夷型銀合歡和相思樹種子，在任何溫度處理下發芽率皆低，僅約8-16%，且發芽不同步，顯示這2種樹種種子能藉由休眠來延長時間尺度的發芽分配，而茄苳、草海桐和水黃皮種子在溫度30/20℃與25/15℃的控溫生長箱平均發芽天數為9-27天，顯示種子不具休眠性。在不同溫度環境下，夏威夷型銀合歡和相思樹種子的發芽表現相似，磨破種皮後之發芽率幾乎達100%，且在低溫20/10℃環境下，種子平均發芽天數分別只需4.2及5.7天，顯示種子休眠解除後具備極大的發芽潛力。進一步研究發現，雖然這2樹種胚根突破種皮後對乾燥敏感，但種子發芽後，夏威夷型銀合歡胚根突出長度至2.00 mm的耐乾燥能力較相思樹高。結論，夏威夷型銀合歡種子具有結構的休眠，解除休眠後的發芽率高，發芽適溫範圍廣，及發芽種子耐旱能力強等特性，推測皆是有利於族群擴張的重要因素。

The seeds of invasive Leucaena leucocephala and five native species Acacia confusa, Bischofia javanica, Scaevola taccada, Pongamia pinnata, Terminalia catappa were studied for germination at various temperatures, and the desiccation tolerance of seeds of L. leucocephala and A. confusa at different germination stages was examined in order to explore the advantages of L. leucocephala population colonization in Taiwan. Result showed that these seeds differed significantly in their germinability. The seed germination percentage of invasive L. leucocephala and native A. confusa was low (8-16%) at alternating temperatures of 30/20, 25/15 or 20/10℃ and at constant 25℃ temperature, while seed germination percentage of native B. javanica, S. taccada and P. pinnata at 30/20 or 25/15℃ was high and mean germination time was 9-27 days. Seed germination percentage of L. leucocephala and A. confusa with seed coat broken was close to 100% and mean germination time was 4 and 6 days, respectively, under a wide range of simulated temperature conditions. Further, radicle protruding seeds of L. leucocephala were more tolerant to desiccation than that of A. confusa as comparison of the radicle protrusion length to 2.00 mm. In conclusion, L. leucocephala seeds have physical dormancy, high germination percentage after dormancy release, a wide range of suitable germination temperatures and desiccation tolerance of radicle protruding seeds, all of which are presumed to be important factors for population colonization.