Watanabe M, Kitaoka S, Eguchi N, Watanabe Y, Satomura T, Takagi K, Satoh F, Koike T
Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan.
Silviculture and Forest Ecological Studies, Hokkaido University, Sapporo, Japan.
Plant Biol (Stuttg). 2016 Jan;18 Suppl 1:56-62. doi: 10.1111/plb.12382. Epub 2015 Sep 13.
The purpose of this study was to obtain basic information on acclimation capacity of photosynthesis in Siebold's beech seedlings to increasing light intensity under future elevated CO2 conditions. We monitored leaf photosynthetic traits of these seedlings in changing light conditions (before removal of shade trees, the year after removal of shade trees and after acclimation to open conditions) in a 10-year free air CO2 enrichment experiment in northern Japan. Elevated CO2 did not affect photosynthetic traits such as leaf mass per area, nitrogen content and biochemical photosynthetic capacity of chloroplasts (i.e. maximum rate of carboxylation and maximum rate of electron transport) before removal of the shade trees and after acclimation to open conditions; in fact, a higher net photosynthetic rate was maintained under elevated CO2 . However, in the year after removal of the shade trees, there was no increase in photosynthesis rate under elevated CO2 conditions. This was not due to photoinhibition. In ambient CO2 conditions, leaf mass per area and nitrogen content were higher in the year after removal of shade trees than before, whereas there was no increase under elevated CO2 conditions. These results indicate that elevated CO2 delays the acclimation of photosynthetic traits of Siebold's beech seedlings to increasing light intensity.
本研究的目的是获取日本北部一项为期10年的自由空气二氧化碳富集实验中，光叶榉幼苗光合作用对未来升高的二氧化碳条件下光照强度增加的适应能力的基础信息。我们在不断变化的光照条件下（去除遮荫树之前、去除遮荫树后的第一年以及适应开放条件后）监测了这些幼苗的叶片光合特性。在去除遮荫树之前和适应开放条件后，升高的二氧化碳并未影响光合特性，如单位面积叶质量、氮含量和叶绿体的生化光合能力（即最大羧化速率和最大电子传递速率）；事实上，在升高的二氧化碳条件下维持了较高的净光合速率。然而，在去除遮荫树后的第一年，在升高的二氧化碳条件下光合速率没有增加。这不是由于光抑制。在环境二氧化碳条件下，去除遮荫树后的第一年单位面积叶质量和氮含量高于之前，而在升高的二氧化碳条件下则没有增加。这些结果表明，升高的二氧化碳延迟了光叶榉幼苗光合特性对光照强度增加的适应。
