典型城区与郊区环境两种灌木生理生化特性比较

选取北京城区与郊区典型样点,针对栽植多年的大叶黄杨（Euonymus japonicus）和小叶黄杨（Buxus sinica subsp.sinica var.parvifolia）成龄植株,分别于春、夏、秋3季取样测定叶片的各项生理生化指标,研究了城区与郊区环境下2种灌木的生理生化特性的差异。结果表明：生长前期（春季）城区车公庄2种灌木的叶绿素总量高于郊区植物园,经过一段时期之后低于植物园（夏秋）。Chlb的城郊变化幅度大于Chla。Chla的变化趋势与Chlb相反造成了Chla/b的大幅度变化。大叶黄杨的叶绿素总量和Chla/b比小叶黄杨受城区环境影响更大。城区环境下2种灌木自由水/束缚水降低,脯氨酸质量分数、丙二醛质量摩尔浓度升高,说明城区环境下2种灌木生理代谢水平降低,膜脂过氧化。城区环境下大叶黄杨的自由水/束缚水、脯氨酸质量分数的变化率较小叶黄杨高,2种灌木丙二醛的变化率相近。综合来看,城区环境下大叶黄杨的生理生化反应比小叶黄杨更敏感。

Comparation of physio-biochemical characteristics of two shrub species in the typical urban and suburban environments in Beijing

To find the seasonal differences in physio-biochemical performances of Euonymus japonicus and Buxus sinica subsp. sinica var. parvifolia growing in urban and suburban environments, adult plants of these two ornamental species were selected in this study and their physio-biochemical characteristics were measured in spring, summer and autumn respectively. The results showed that the total chlorophyll contents of these two shrubs growing in urban area of Beijing were both higher than that of suburban counterparts in spring, but lower in summer and autumn. In suburban environment, the changes in contents of chlorophyll b of these two shrubs were greater than chlorophyll a. The different trends in the contents of chlorophyll a and b resulted the major changes in the ratios of chlorophyll a to b. Furthermore, the urban environment imposed a greater effect on the total chlorophyll contents of Euonymus japonicus than that of Buxus sinica subsp. sinica var. parvifolia. In urban environment, the ratios of free to bound water in these two shrubs decreased, while the proline and malondialdehyde （MDA） contents increased, which indicated the low metabolism and the peroxidation of cell membranes. The changes in the ratio of free to bound water and proline content of Euonymus japonicus were smaller than that of Buxus sinica subsp. sinica var. parvifolia in urban area, but the changes in MDA contents were similar. In general, the physio-biochemical characteristics of Euonymus japonicus were more sensitive than that of Buxus sinica subsp. sinica var. parvifolia in urban environment.