入侵物种三裂叶蟛蜞菊挥发物的化感作用研究

对华南地区重要外来入侵物种三裂叶蟛蜞菊挥发物的化感作用进行了研究,以揭示该物种的入侵机制。采用水蒸气蒸馏法提取三裂叶蟛蜞菊地上部分的挥发油,提取率为2.58‰(质量比)。以稗草、三叶鬼针草和青葙3种杂草种子为供试对象,用种子萌发法测定了三裂叶蟛蜞菊挥发物的化感作用活性。结果表明:三裂叶蟛蜞菊的茎叶在密闭系统中产生的挥发性物质对稗草、三叶鬼针草和青葙的幼苗生长有显著抑制作用。稗草的根长、苗高和鲜质量分别比对照减少49.1%、35.0%和27.3%,三叶鬼针草的分别比对照减少18.8%、20.9%和28.6%,青葙的分别比对照减少62.9%、21.2%和50.0%。水蒸气蒸馏法所得的挥发油对稗草、三叶鬼针草和青葙的幼苗生长也有显著抑制作用,且抑制作用随着浓度的增大而增强。稗草的根长、苗高和鲜质量分别比对照减少88.2%、58.3%和45.5%,三叶鬼针草的根长、苗高和鲜质量分别比对照减少38.6%、34.5%和71.4%,青葙的根长、苗高和鲜质量分别比对照减少83.7%、51.5%和75.0%。结论:三裂叶蟛蜞挥发物具有化感作用,其作用机理值得深入研究。

Allelopathic potentials of volatiles from Wedelia trilobata L.

The allelopathic potentials of volatiles of Wedelia trilobata L were investigated to determine the role of allelopathiy in suc- cessful invasion of this alien plant in South China. Methods: The allelopathic potentials of Wedelia trilobata L. were determined by the seed germination and seedling growth of Echinochloa crusgalli (L.) Beauv., Bidens pilosa L. and Celosia argentea L. Results: The volatiles released from leaves and stems of W. trilobata L. in an airproof system significantly inhibited the seedling growth of E. crusgalli, B. pilosa and C. argentea. Compared to the control, root length, shoot length and fresh weight of E. crusgalli decreased by 49.1%, 35.0% and 27.3%, respectively; these of B. pilosa decreased by 18.8%, 20.9% and 28.6%, respectively; and these of C. argentea decreased by 62.9%, 21.2% and 50.0%, respectively. Essential oil obtained from the steam distillation of fresh leaves and stems also significantly inhibited the seedling growth of the three tested weed species. The inhibition of the essential oils was en- hanced with increase of its concentration. Compared to the corresponding control, root length, shoot length and flesh weight of E. crusgalli decreased by 88.2%, 58.3% and 45.5%; these of B. pilosa decreased by 38.6%, 34.5% and 71.4%, respectively; and the root length, shoot length and fresh weight of C. argentea decreased by 83.7%, 51.5% and 75.0%, respectively. Conclusion: The results indicate that volatiles of W. trilobata have allelopathic potentials which may serve as an important mechanism of successful invasion of this alien species.