光度及酸鹼處理對大花咸豐草種子發芽之影響

大花咸豐草自1976年被引進臺灣後，短短數十年已遍佈全島海邊、低海拔農田及荒野，甚至2300公尺之高海拔地區亦有分布，為一侵占性強且高危害力之外來植物。為了解大花咸豐草種子在不同土壤反應及常用於雜草防治之斷光處理下，種子發芽與幼苗發育之潛力，本試驗比較12/12小時光照及連續黑暗處理下，不同酸鹼處理(pH 2.5-12)對大花咸豐草種子發芽，以及幼苗胚根與胚軸發育的影響。試驗結果顯示，不同pH處理對其發芽率有顯著影響，但光度處理間及pH與光度之交感作用則無顯著差異。在12/12小時光照處理中，大花咸豐草種子發芽率最低與最高為pH 2.5 (52%)及pH 7 (90%)；而黑暗處理下，發芽率最低同樣為pH 2.5 (63%)，最高為pH 11 (84%)，但與pH 7之發芽率差異不顯著。比較不同的pH處理對幼苗胚根及胚軸發育的影響可知，不論光照與否，胚根長度均以pH 5顯著高於其他處理，於pH 2.5及pH 8以上時，其發育顯著受到抑制達65%以上；而胚軸部分結果顯示，不論光照處理為何，不同的pH處理下，均以pH 7處理之長度最長，隨著pH降低或提高，胚軸受抑制程度亦隨之增加。整體而言，大花咸豐草雖可在廣泛的pH範圍下，均有很高的發芽潛力，但胚根與胚軸的發育則明顯對不同pH處理較為敏感，強酸性或偏鹼性環境對其幼苗之胚根與胚軸發育則有負面影響。

關鍵字

大花咸豐草；酸鹼度；光度；種子；發芽

並列摘要

Bidens pilosa L., a highly invasive species, has been introduced to Taiwan by a beekeeper in 1976. Over the past decades, this species has soon invaded much seashore, farmlands and abandoned fields at low altitudes of Taiwan. To elucidate its seed germination potential interaction between light/dark and soil reaction, seed germination and seedling development response of this species to light/dark regime and wide pH range (2.5-12) were investigated in laboratory experiments. The results showed significant difference in different pH treatment. However, neither light treatment nor interactions between light and pH showed significant difference. Seed germinated 52% to 90% in buffer solutions of pH 2.5 to pH 12 under 12/12 photoperiod regime and germinated 63% to 84% in the same pH range under dark regime. Optimum pH for radicle growth was pH 5. Radical growth was inhibited exceed 65% above pH 8 or below pH 4. Optimum pH for hypocotyl growth was pH 7. Hypocotyl growth decreased above or below this treatment. Overall, seeds of B. pilosa L. can germinate to high percentage over a wide of pH, however, radical and hypocotyl growth of this species are more sensitive to alkali and extreme acid environment than germination.

並列關鍵字

Bidens pilosa L. var. radiata ； pH ； Light ； Seed ； Germination

國際替代計量

光度及酸鹼處理對大花咸豐草種子發芽之影響

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