Department of Agriculture, University of Queensland, 4068, St. Lucia, Australia.
Photosynth Res. 1983 Jun;4(2):137-44. doi: 10.1007/BF00052375.
The distribution of net photosynthetic activity of leaves was measured in a mixed grass (Setaria sphacelata var. sericea)-legume (Desmodium intortum) pasture stand using a method based on concurrent measurement of the rate of CO2 exchange, and (14)CO2 dosing followed by rapid harvesting according to height strata. Comparisons were also made between plots which differed in the period of regrowth following defoliation.The usual superiority of leaf net photosynthetic rates of a C4 grass, compared with C3 legume leaves, was found in the upper, well illuminated strata. These rates were, however, much lower than those usually described for horizontally exposed leaves, primarily because leaves in the pasture stand were inclined to the horizontal. At greater depth in the canopies, the superiority of rates in the grass was less evident, and consequently the relative contributions of grass and legume to canopy photosynthesis became more dependent on their leaf area indices.Attention is drawn to the relative simplicity of the method for examining the contribution of leaves, which may differ according to species or position in the canopy, to productivity of the whole stand.
利用一种基于同时测量 CO2 交换率和（14）CO2 剂量并根据高度层进行快速收获的方法，测量了混播草地（狼尾草变种丝毛）-豆科（金合欢）草地中叶片净光合活性的分布，这些草地在除叶后恢复的时期存在差异。通常情况下，C4 草叶片的净光合速率要优于 C3 豆科叶片，这在光照良好的上层区域尤为明显。然而，这些速率远低于通常描述的水平叶片的速率，主要是因为草地中的叶片倾向于水平方向。在树冠的更深层，草的优势不那么明显，因此草和豆科植物对树冠光合作用的相对贡献更多地取决于它们的叶面积指数。该方法用于检查根据物种或树冠位置而有所不同的叶片对整个群落生产力的贡献的相对简单性引起了人们的关注。
