Abstract
We developed a positron detector system to analyze water behavior in a plant stem, non-destructively. Water was labeled by 15O ([15O]water) and the trace amount of water uptake was determined through the system. The calibration between the amount of [15O]water and the counts of the detector system was obtained using a stem-mimic phantom tube. A three-week-old soybean plant was supplied with [15O]water from the root and the activity of [15O]water in the 1-cm-epicotyl was measured. The amount of [15O]water was increased with time linearly from 5 to 15mim, and the water amount was estimated to be about 15μl through calibration. Because the volume of vessel at the epicotyl, in the length of 1cm, was 2.1±0.3μl, the leak-flow of water from the vessel was suggested for the first time.
