Department of Biology, University of Dayton, Dayton, Ohio 45469.
Plant Physiol. 1979 Sep;64(3):361-5. doi: 10.1104/pp.64.3.361.
Export of labeled material derived by continuous photosynthesis in (14)CO(2) was monitored with a Geiger-Müller detector positioned next to an exporting leaf blade. Rate of export of labeled material was calculated from the difference between rates of retention and net photosynthesis of labeled carbon for the observed leaf. Given certain conditions, including nearly constant distribution of labeled material among minor veins and various types of cells, count rate data for the source leaf can be converted to rate of export of carbon. Changes in counting efficiency resulting from changes in leaf water status can be corrected for with data from a transducer which measures leaf thickness.Export data agreed with data obtained by monitoring the arrival of (14)C in the sink region; isolated leaves gave values near zero for export. The method allows continuous nondestructive measurement of export of labeled carbon from a given leaf on an intact plant. The technique detects changes in export with a resolution of 10 to 20 minutes.
用盖革-弥勒探测器监测置于导出叶片旁的（14）CO2 中连续光合作用产生的标记物质的导出。标记碳的导出速率是根据观察到的叶片的标记碳保留率和净光合作用率之间的差异计算的。在某些条件下，包括标记物质在小叶脉和各种类型的细胞中几乎均匀分布，源叶的计数率数据可以转化为碳的导出速率。由于叶片水分状况的变化而导致的计数效率的变化可以通过测量叶片厚度的传感器的数据进行校正。导出数据与通过监测（14）C 在汇区的到达而获得的数据一致；分离的叶片的导出值接近零。该方法允许在完整植物上对指定叶片的标记碳的导出进行连续非破坏性测量。该技术以 10 到 20 分钟的分辨率检测导出的变化。
