重金属对8种园林植物种子萌发及幼苗生长的影响

选择8种常见园林草本植物（黑麦草、高羊茅、早熟禾、剪股颖、狗牙根、金鸡菊、白三叶、非洲凤仙）的种子，分别设置不同浓度梯度，利用水培方法，研究重金属Zn、Pb、Cu、Cd胁迫对植物种子萌发及幼苗生长的影响。结果表明，重金属胁迫对园林草本植物种子的发芽和生长的影响因重金属及植物种类而异。Zn、Pb除对白三叶种子萌发有显著抑制作用，对其他7种植物均有促进作用，Cu、Cd对8种植物的种子萌发则以抑制为主。Zn、Pb对植物幼苗的生长具有不同程度的促进作用；Cd促进早熟禾、金鸡菊、狗牙根和剪股颖的苗生长，但会抑制其他4种植物幼苗的生长；4种金属中Cu毒性最强，对植物幼苗生长均以抑制作用为主，低浓度时就会出现“无根苗”现象。 Zn、Pb、Cu、Cd对植物根系生长均表现出强烈的抑制作用。

Effects of Heavy Metal Stress on Seed Germination and Seedling Growth of Eight Urban Plants

Eight urban herbaceous plants （Lolium perenne,Festuca arundinacea,Poa pratensis,Agrostis palustris,Cynodon dactylon,Coreopsis lanceolata,Trifolium repens,Impatiens walleriana） were cultivated in Zn,Pb,Cu and Cd solutions of a series of concentrations to investigate the effects of heavy metals on seed germination and seedling growth.The results indicated that the effects of seed germination and seedling growth varied with metals and plants species.Zn and Pb inhibited seed germination of Trifolium repens,but increased in other species.Both Cu and Cd inhibited seed germination to all the eight species.For seedling growth,all species were promoted differently by Zn and Pb but extremely decreased by Cu solutions,resulting in rootless seedlings even in low concentrations.Except for Poa pratensis,Cynodon Dactylon,Coreopsis lanceolata and Agrostis palustris,Cd also showed stress to the urban herbaceous plants.All the metals showed toxicity to root growth of all the species studied.