紫茎泽兰化感作用对9种草本植物种子萌发的影响

【背景】紫茎泽兰是一种入侵我国的世界性恶性杂草,给当地的农、林、畜牧业生产造成严重的经济损失,使生态环境面临"绿色灾难"。紫茎泽兰的化感作用是其成功入侵的重要原因,其化感物质对当地植物的生长具有明显的抑制作用。【方法】利用培养皿滤纸法研究了紫茎泽兰叶片水提液对9种草本植物种子萌发的影响,这些植物包括紫茎泽兰入侵早期直接与之竞争的云南草本植物:鲁梅克斯、高丹红、鸭茅(安巴)、苕子、胡枝子,以及为替代控制紫茎泽兰而引进的外来优良牧草:紫花苜蓿(敖汉)、白三叶(海发)、红三叶、黑麦草(速达)。【结果】紫茎泽兰叶片提取液对9种受体植物种子萌发均具有化感作用。低浓度提取液对受体植物的化感作用较弱(对部分植物种子萌发有促进作用);高浓度提取液对受体植物的化感作用较强,且能降低种子发芽率及发芽速率,其中,发芽速率对化感作用更敏感。不同植物对紫茎泽兰化感作用的敏感程度不同,鲁梅克斯、鸭茅和苕子对紫茎泽兰的化感作用较敏感;黑麦草、胡枝子和高丹红最不敏感;紫花苜蓿、红三叶和白三叶对低浓度紫茎泽兰叶片水提液不敏感,对高浓度提取液较敏感。【结论与意义】不同植物种子对紫茎泽兰化感作用的敏感性存在差异,研究结果有利于了解紫茎泽兰成功入侵的机制,并可为筛选具有替代控制潜力的优良牧草奠定基础。

Allelopathic effect of Ageratina adenophora on seed germination of nine herbaceous species

Background]Ageratina adenophora is one of the worst invasive alien weeds in China.It has caused serious economic losses to agriculture,forestry and livestock,severely damaging the ecology and environment of China’s native habitat.It was confirmed that allelopathy of A.adenophora has been a contributing factor in its invasion,some allelochemicals from A.adenophora have severe negative impacts on the native receptor plants,significantly inhibited the growth of receptor plants.Method]The allelopathic effects of aqueous leaf extract of A.adenophora on seed germination and seedling growth of nine herbaceous species in Yunnan Province were determined.These plants included five herbaceous species that compete directly with A.adenophora during the early stage of its invasion:Rumex patientia,Sorghum vulgare,Dactylis glomerata cv.Anba,Vicia dasycarpa and Lepedeza bicolor,and four pasture species introduced to replace A.adenophora:Medicago stive cv.Aohang,Trifolium repens cv.Haifa,T.pratens and Lolium perenne cv.Suda.Result]The aqueous leaf extract of A.adenophora could inhibit seed germination and seedling growth in all the nine species,and its effect was concentration dependent,increasing with concentration.Seed germination speed was more sensitive to the extract than seed germination rate,which might be the most sensitive index to judge allelopathy S.vulgare,Lepedeza bicolor and Lolium perenne were not sensitive to the aqueous leaf extracted allelochemicals of A.adenophora.Conclusion and significance]Different herbaceous plant species seeds has various sensitivities on effects of aqueous leaf extract of A.adenophora.These results extend our understanding of the invasion mechanism of A.adenophora and to find some potential pasture plants which can displace A.adenophora in invaded regions.