互花米草与芦苇耐盐生理特征的比较分析

Comparative Study on Physiological Characteristics Between an Invasive Plant Spartina alterniflora and Indigenous Plant Phragmites communis

以天津滨海滩涂外来植物互花米草和本地种芦苇为研究对象,对两种植物根、茎、叶3个器官保护酶(超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT))和膜脂过氧化产物丙二醛(MDA)、游离脯氨酸、可溶性糖以及质膜相对透性及其季节动态变化进行了测定。结果表明:(1)互花米草体内SOD、POD、CAT酶活性、游离脯氨酸、可溶性糖含量在整个生长季节较芦苇偏低;(2)游离脯氨酸和可溶性糖是互花米草和芦苇体内重要的有机渗透调节物质;(3)两种植物根、茎、叶的质膜相对透性在整个生长季节基本保持稳定,但互花米草质膜相对透过性高于芦苇。该研究有利于解释互花米草适应潮间带生存环境的部分机制,并且从生理生态学特性角度说明其竞争力高于芦苇的原因。

Spartina alterniflora is a rhizomatous perennial, native to the Atlantic and Gulf coasts of North America, occurring from Quebec and Newfoundland to Florida and Texas. In China, S. alterniflora was introduced to stabilize shorelines and increase vegetative cover in 1979, and now flourished in many inter-tidal zones of gulfs and estuaries with its spread. As a consequence of rapid globalization, greatly increased emphasis is placed on research of the ecology of invasive plants. S troduced into Haihe estuary in 1998, it has gradually occupied a large area of the indigenous plant Phragmites communis zone, and P. communis was squeezed out into a higher plot. In this study, the POD, CAT, SOD activities, the contents of free proline and soluble sugar, and the relative permeability of plasma membrane in different organs between the two species were measured and compared. The experiments were performed during the growing season in 2005 at Haihe delta wetland, in E 117°45′, N 39°03′. The main experimental results were as follows：The SOD, POD, CAT activities, free proline and soluble sugar contents of S. alterniflora were lower than those of P. communis ; Free proline and soluble sugar were two compatible substances and played important roles in keeping osmotic balance in both S. alterniflora and P. communis; Relative plasma membrane permeability tended to remain stable in both species, and maintain at a higher value in S. alterniflora than that in P. communis as a whole.These results could be helpful in explaining the physiological and ecological mechanisms of S. alterniflora with respect to its strong competitive ability.