Turitzin S N, Drake B G
Smithsonian Radiation Biology Laboratory, 12441 Parklawn Drive, 20852, Rockville, Maryland, USA.
Oecologia. 1981 Feb;48(1):79-84. doi: 10.1007/BF00346991.
A seasonal decline in the photosynthetic efficiency of a Chesapeake Bay salt marsh occurs concurrently with a seasonal shift in foliage canopy structure from erect- to horizontal-leaved. Infrared gas analysis was used to measure net photosynthesis by isolated sections of marsh before and after the canopy was subjected to experimental manipulations designed to mimiic the natural canopy change. During June and July when the canopy was normally erect, inducing horizontal leaf orientation reduced net photosynthesis by 50 percent. In late August, when the canopy was naturally horizontal, making the leaves erect increased photosynthesis. These results support the hypothesis that the normal seasonal decline in photosynthesis is due, at least in part, to the shift in canopy structure.
切萨皮克湾盐沼光合效率的季节性下降与叶冠层结构从直立叶向水平叶的季节性转变同时发生。在叶冠层接受旨在模拟自然冠层变化的实验操作前后，利用红外气体分析法测量了盐沼隔离区域的净光合作用。在6月和7月，当冠层通常为直立状态时，诱导叶片水平方向会使净光合作用降低50%。在8月下旬，当冠层自然呈水平状态时，使叶片直立会增加光合作用。这些结果支持了以下假设：光合作用正常的季节性下降至少部分归因于冠层结构的变化。
