Water gradient profiles at bean plant roots determined by neutron beam analysis

We present profiles of the water gradient near the roots of bean plants measured by neutron beam analysis. Three kinds of bean plants were grown in cylindrical aluminum containers and were irradiated by thermal neutrons from a research reactor, JRR-3M, installed at Japan Atomic Energy Research Institute. After penetrating the sample, neutrons were converted to light by a fluorescent converter and the resulting photons were counted by a cooled CCD camera. Taking the projection images at different angles of the samples, CT images as well as simple projection images were constructed. It is seen here, for the first time, that water is significantly concentrated within the first 1 mm from the root surface in all three kinds of the plants. Soybean root grown under stress from added aluminum was studied by calculating root volumes and total root surface area from the spatial images. The suppression in root development as calculated from this nondestructive in-situ method correlates well with destructive techniques.