臺灣北部地區植物群落之植物毒性潛能

Abstract

植物毒質(Phytotoxin)在植物社會消長變遷過程中的重要性已有多方面的報告。此報告大多來自乾旱、半乾旱及地中海型氣候區的研究，但在熱帶及亞熱帶此方面的研究報告尚不多見。本論文乃就台灣北部地區(包括臺北、基隆、竹仔湖等地)常見植物來研究其植物毒質潛能。 試驗材料包括植物的鮮葉、枯葉及其樹冠下的土壤，分夏冬二季採集。植物毒性是以兩種生物分析加以測定。由生物分析結果顯示在pH值、滲透濃度及元素含量不影響的情形下，大部分植物的鮮葉、枯葉及其土壤水溶萃取液對萵苣種子發茅幼根生長具有顯著的抑制作用。更進一步做植物毒質鑑定時，發現許多樁物毒質為酚類化合物，那是P-hydroxybenjoic，P-coumaric,Vanillic,SyringicFerulic，及(o-Hydroxyphenyl)aceticacids，其中最常見者為(o-Hydroxypheny)aceticacid，另外發現五種未知高毒性化合物及對ninhydrin正反應的斑點。 比較鮮葉及枯葉水溶萃取液中酚類化合物的相對量時，發現前者所含的量相對大於後者，但由生物分析結果顯示多數植物的鮮葉與枯葉毒性差異不顯著，因此推測另有其他植物毒質也存在水溶萃取液中。 由土壤加鹼分解萃取液中，發現大部分土壤中的酚類化台物組成相同，包括Ferulic，p-Coumaric,Syringic,Vanillic,p-Hydroxybenjoic及(o-Hydroxyphenyl)aceticacid等，唯相對量各有不同。 比較夏冬二季鮮葉、枯葉及土壤水溶萃取液之毒性及其元素含量，發現二季間役有頭著之差異，可能與北部雨量豐富、乾季短暫有關。

Although phytotoxins that ploy on important role in the succession of plant communities have been elucidated in the arid, semi_arid and mediterranean areas, only a limited inJormation is available in the area of tropical and subtropical climate. Thus this study is trying to evaluate the phytotoxic potential of twenty_five common species in northern Taiwan. Fresh leaves, litter (unrotten) end soils underneath the plants were collected in sunmor eeh winter separately. The phyto_toxicity was determined by two bioassay methods. Aqueous sxtracts of most species exhibited significant inhibition en the radical growth of lettuce on sponge bioassay, when the effects of pH, osmotic concentration and cations were not significant. The chromatographic bioassay showed 12 toxic spots. Six of them, p-hydroxybenzoic, p_cenmaric, vanillic, syringic, forulic, and (p-hydroxyphenyl) acetic acids, are the common phytotexic compounds, while the rest of them have not been identified, Although the phenolic content of the leaf litter was relatively lower than that of fresh leaves, the texicit/ revealed by the former was almost the same as the latter. This suggested that some non_phenolic toxic compounds may present in the litter. p_Coumaric, p-hydorxybenzoic, syringic, vanillic, ferulic, and (o_hydroxyphenyl)_. acetic acids were found to be widespreaded in various soils. However, the amount of each toxin present in each soils sample are relatively different. The phytotoxicity and the amount of cations in plant materials were not significantly affected by seasons. This was probably ascribed to the heavy rainfall and short duration of drought period of the study area.