The ROOTS project is a collaboration between Texas A&M Agrilife, Harvard University, Soil Health Institute, NIST, and ABQMR.
During Phase I of the project, ABQMR built an MRI system that can be lowered into the ground, around plant roots and acquire an image in-situ. The system is composed of a resistive (electro) magnet (2 MHz proton frequency), gradient coils in three dimensions and a quadrature RF coil, shown in Figure 1.
The imaging region is a cylindrical region of approximately 10" height and 10" diameter. To stabilize the plant and soil around it, a 10" OD piece of PVC pipe is hydraulically driven into the ground. A larger diameter, sheet-steel cylinder is driven into the ground around the PVC and when lifted out, it removes an annular region of soil.
The magnet is then lowered into this space, energized and used to acquire images of the plant roots. In parallel with field testing the resistive magnet, a high temperature superconducting magnet (Super Mag) is being built. The Super Mag will be able to reach a higher magnetic field (6 MHz proton frequency) which will increase the signal to noise in the images and/or reduce the imaging time.
The rotating figure shows a three-dimensional image of sorghum roots, Figure 2.
The current standard for studying root architecture is to dig up the roots, wash them off and take images of them. The root MRI system allows agronomists to take in-situ measurements of root architecture as it appears in a natural soil.
G. Cody Bagnall, Neha Koonjoo, Stephen A. Altobelli, Mark S. Conradi, Eiichi Fukushima, Dean O. Kuethe, John E. Mullet, Haly Neely, William L. Rooney, Karl F. Stupic, Brock Weers, Bo Zhu, Matthew S. Rosen, Cristine L. S. Morgan, "Low-field magnetic resonance imaging of roots in intact clayey and silty soils," Geoderma 370, 114356 (1 July 2020).