Rhizosphere

The goal of this project is to develop the next generation of optical instrumentation to monitor the function and structure of root systems by exploiting the light-piping properties of plant stems. Roots play an important role in overall plant health and the urgency of global warming has made technologies to non-invasively monitor plant health increasingly important.

Due to the optically opaque nature of soil, common optical methods to measure root growth underground rely on rhizotrons: small, glass-walled observations laboratories which allow the root growth to be directly visualized as it grows alongside the windows. Other methods to measure the root structure include X-ray computed tomography and magnetic resonance imaging. However, these methods suffer from a lack of contrast and other complicating factors such as large background signals from the soil.

This project proposes to leverage a discovery from the 1980s that the internal structure of plant stems and roots channels light within the internal structure of the plant itself. This discovery, which until now has been largely unexplored in the biophotonics community, has the potential to enable new optical strategies to non-invasively measure key quantities of the microbiome such as root structure, function, and water uptake. The non-invasive nature of the measurement is critically important as it not only enables the measurements to be made without disturbing the natural interaction of the plant with the soil surrounding it, but also allows the same plant to be measured over time to monitor its growth.

The instrumentation development will be pursued in three main stages: design exploration and proof-of-concept prototype, device characterization of the optical and light-piping properties of plant tissues, and optical instrumentation development to exploit the light-piping properties to non-invasively interrogate the structure and function of the below-ground portion of the plant.

Acknowledgements

This project is supported by the National Science Foundation via Award #2238365.