入侵植物刺苍耳对小麦和苜蓿种子的化感作用

采用生物实验法，研究刺苍耳（WTBX]Xanthium spinosumWTBZ]）不同构件的水浸提液对小麦和苜蓿种子的化感效应。结果表明:刺苍耳植株不同构件的提取液对小麦和苜蓿种子的萌发均具有较强的抑制作用，而根、茎和叶水浸液产生显著抑制作用的起始浓度分别为0.012 50 g·mL-1，且化感作用随浸提液浓度的增加而增强。刺苍耳根、茎、叶水浸液对小麦和苜蓿种子萌发的抑制, 不仅表现为降低种子的最终发芽率，还表现为延长种子的萌发周期。不同构件水浸液的化感效应强度整体表现为：叶＞根＞茎，并且化感效应强度随水浸液浓度的增加而增强。

Allelopathic Effect of Xanthium spinosum on Seeds of Triticum aestivum and Medicago sativa

Xanthium spinosum WTBZ] is an annual invasive species, and it was originated from South American. It has a wide adaptability to barren soil and saline or alkaline soil as well as flood and drought conditions. Just because of its transmission capability, WTBX]X.spinosumWTBZ] devastates the native biodiversity, plant distribution, community formation and intercrop evolution. In this paper, the aqueous extract from the roots, stems and leaves of WTBX]X.spinosumWTBZ], at concentrations of 0.012 5, 0.250, 0.050 g·mL-1 and 0.100 g·mL-1, was used as a treatment solution to study its allelopathic effect on seed germination of WTBX]Triticum aestivumWTBZ] and WTBX]Medicago sativaWTBZ]. The results revealed that the seed germination of WTBX]T.aestivumWTBZ] and WTBX]M.sativaWTBZ] was significantly inhibited by the aqueous extract at concentration ≥ 0.012 5 g·mL-1. All the aqueous extract of the roots, stems and leaves inhibited seed germination of WTBX]T.aestivumWTBZ] and WTBX]M.sativaWTBZ], which not only reduced the germination rate of seeds but also prolonged the period of ultimate germination. The allelopathic effect of the aqueous extract was in an order of stem > leaf > root, and the effect was intensified at higher extract concentration. The results are of the theoretical significance and practical value in conducting biological control of exotic species and developing new biological pesticide.