遮阴对几种绿化植物光合特性和生长的影响

通过对照试验,比较测定不同光强生境(全光照,45%、75%遮光率)对上海9种城市绿化植物光合特性和生长的影响。结果表明,随着遮光率的增加,植物的日均净光合速率依次降低,日均净光合速率与日均光合有效辐射的比值依次升高;植物的叶绿素质量浓度总体呈增加趋势,叶绿素a/叶绿素b值无显著差异,叶绿素a/叶绿素b值几乎都小于3;株高增量和叶片厚度缺乏规律性变化趋势,可能与由遮阴引起的其他小气候因子变化有关。对植物各项生理特性进行相关分析,其中叶绿素质量浓度在不同光照条件下均与叶片厚度呈显著或极显著正相关,在全光照下,日均光合有效辐射和叶绿素质量浓度、叶片厚度分别呈极显著和显著正相关;而在75%遮阴下日均光合有效辐射和株高增量呈极显著相关。

Effects of Shades on Photosynthetic Characteristics and Growth of Several Species of Afforestation Plants

An experiment was conducted to study the effects of different light treatments (full light, 45% shade and 75% shade)on photosynthetic characteristics and growth of nine species of urban afforestation plants in Shanghai, which are Weigela florida' Red prince' , Spiraea×bumalda' Gold flame', Spiraea×bumalda' Gold Mound' , Berberis thumbergii f. atropurpurea, Ligusrum ovalifolium f. aweum, Ewnymus japonicus var. aurea-marginatus, Hypericum monogynum, Loropetalum chinense var. rubrum, and Mucuna sempervirens. Results indicated that with the increase of shade ratio, the average net photosynthetic rate of the plants reduced in turn, while the ratio of average net photosynthetic rate to average Photosynthetically Active Radiation (PAR) heightened in turn. The chlorophyll contents showed a general upward trend, and no obvious difference was found between chlorophyll a/b ratios, most of which were less than 3. No regular variations in plant height increment and leaf thickness were observed, which may be related with the changes of other climatic factors caused by the shade treatment. Correlation analysis of physiological characteristics of the plants exhibited that there were significant or extremely significant positive correlation between chlorophyll content and leaf thickness under different shade levels. There was an extremely significant correlation between average PAR radiation and chlorophyll content and a positivecorrelation between average PAR and leaf thickness in the full sunlight treatment, and an extremely significant positive correlation between average PAR and plant height increment was also observed in 75% shade treatment.