尾叶桉对四种豆科植物的化感作用

以尾叶桉(Eucalyptus urophylla)为研究对象,测定了其叶片自然挥发物和不同浓度水抽提物对台湾相思(Acacia confusa)、大叶相思(Acacia auriculaeformis)、马占相思(Acacia mangium)和南洋楹(Albizia falcataria)的化感作用。结果表明:①叶片自然挥发物对4种植物的种子萌发均无显著影响,但对台湾相思和南洋楹的茎生长有极显著的抑制,而对大叶相思和马占相思的根生长则有极显著的促进;②清水浸提24 h所得的叶片水抽提物对4种植物的种子萌发均无显著影响,对台湾相思、马占相思和南洋楹的根和茎生长有极显著的抑制,而对大叶相思的茎生长则有极显著的促进;③清水浸提72 h并减压浓缩后,配成的不同质量浓度的叶片水抽提物对4种植物的种子发芽率的影响都较小,对根生长的抑制作用随浓度的升高而增强,而对大叶相思、马占相思和南洋楹茎生长的影响则有低浓度促进、高浓度抑制的趋势。尾叶桉叶片向环境中释放的挥发性和水溶性物质确实对4种豆科植物造成了影响,且不同浓度下其作用的程度及性质有所不同。大叶相思种子萌发和幼苗生长所受到的抑制作用最不明显,可作为较理想的尾叶桉伴生树种,以提高桉树人工林的生物多样性。

Allelopathic Effects of Eucalyptus urophylla on Four Leaume Species

Eucalyptus urophylla was used to examine its allelopathic effects on four Leaume species: Acacia confusa,Acacia auriculaeformis,Acacia mangium and Albizia falcataria by way of laboratory bioassay with fresh leaf volatiles,as well as various concentration of leaf water extracts.The results showed that the evaporating substances did not have significant influences on the seed germination of the four plants.However,the stem growth of A.confusa and A.falcataria were remarkably inhibited,while the root growth of the other two were significantly improved.The leaf water extracts leached for 24 hours had no considerable impact on the seed germination of the four plants,either.But they greatly decreased the stem growth of A.confusa,A.mangium and A.falcataria,while greatly increased the stem growth of A.auriculaeformis.On the other hand,the leaf water extracts leached for 72 hours had slight influences on the seed germination of the four plants,when the root elongation presented a downward trend as the inhibitory effects strengthening with increasing water extract concentration.Meanwhile,leaf water extracts had a promoting effect at low concentrations and a restraining effect at high concentrations on the stem growth of all recipient plants except for A.confusa.The volatile and water-soluble substances released by E.urophylla did have influences on the growth of these four Leaume species,and the extent together with property varied with different concentrations.A.auriculaeformis was least sensitive to allelopathic effects and thus could be used as an ideal accompanied plant of E.urophylla.