中文摘要：

在温室内，以原沉积物（CK）和分别添加0．24％与0．48％氯化铵（SN，和SN，）的沉积物作为底质培养沉水植物，研究了穗花狐尾藻对高浓度铵态氮胁迫的生理响应．结果表明：不同处理沉积物、间隙水和上覆水中铵态氮浓度分别在12．35～870．32mg·kg^-1、1．09～1036．05mg·L^-1和0．10—24．30mg·L^-1，与CK相比，SNi和SN2处理的穗花狐尾藻生物量、株高和根长分别降低了19．69％和81．16％、15．66％和55．52％与45．72％和67．65％．不同处理根系和叶片SOD活性均表现为SN2〈SN2〈CK；叶片过氧化物酶（POD）和过氧化氢酶（CAT）活性均表现为SN2〈SN1〈CK，但SN。和SN2根系POD和CAT活性则显著高于CK；SN1、SN2叶片和根系丙二醛（MDA）含量分别比CK提高了46．30％、82．75％和19．66％、55．19％．不同浓度铵态氮对穗花狐尾藻均具有毒害作用，而且铵态氮浓度越高，植物生理响应越明显．

英文摘要：

With the sediment applied with 0, 0. 24%, and 0. 48% NH4Cl （treatments CK, SN1, and SN2 ） as the substrate, a greenhouse experiment was conducted to study the physiological responses of MyriophyUum spicatum to ammonium nitrogen. The NH4^＋ -N concentration in the sediment, pore-water, and overlying-water ranged in 12. 35-870. 32 mg·kg^-1 , 1.09-1036.05 mg·L^-1 , and 0. 10-24. 30 mg·L^-1 , respectively. Comparing with those in CK, the plant height, root length, and fresh biomass of M. spicatum in treatments SNl and SN2 decreased by 15.66% and 55.52% , 45.72% and 67.65% , and 19.69% and 81.16% , respectively. The SOD activity in M. spicatum leaves and roots was SN1 〈 SN2 〈 CK, but the peroxidase （POD） and catalase （CAT） activities in the leaves were SN2 〈 SN2 〈 CK, while those in the roots were significant higher in SN1 and SN2 than in CK. The malondialdehyde （MDA） contents of leaves and roots in SN1 and SN2 were increased by 46.30% and 82.75%, and 19.66% and 55.19%, respectively. It was suggested that NH4^＋ -N had toxic effects on M. spicatum, and the higher the NH4^＋ -N concentration in sediment, the more obvious the physiological responses of M. spicatum exhibited.