Development of a simple, mobile MRI plant imager

The application of non-invasive imaging technologies has had a large impact on the study of plant water relations. Magnetic Resonance Imaging (MRI) has made it possible to image the presence of water or the appearance of emboli in the xylem, or to measure, visualize and quantify flow. However, due to the cost, size and specialized nature of the MRI equipment, so far the method has only been applied to plants by a few laboratories world-wide. To make the method more accessible, but also make it available for use in the greenhouse or field, we constructed a basic, mobile MRI imager for plants, maximizing for making it cheap and simple to use.At the basis of this work was the construction of a mobile 0.25 T, 45 mm gap, C-shaped permanent magnet with a weight of about 16 kg, suitable for MR imaging of objects up to 20 mm diameter. The magnet was fitted with a set of custom built plane-parallel imaging coils, designed for maximum field of view and image resolution, while still offering open access for plant stems. Using a permanent magnet is beneficial due to low purchase and running costs, since neither any power nor liquid gases are required to run it.In a first demonstration experiment we investigated the effect of drought stress on young spruce and beech trees during a 40 day dry down experiment. Considering the simplicity of the setup and the small size of the magnet, surprisingly highly resolved images could already be acquired with the very first protoype. By means of this data that was obtained weekly over the whole dry down period, insights could be gained on where emboli occur first in the stems of the two species