Towards Novel Techniques for Root Phenotyping Using GPR.

The ability to phenotype roots in situ is a valuable tool that provides information on carbon sequestration potential, water-seeking strategies, and line selection for plant breeders. One technique for root phenotyping is to measure differences in soil moisture and use this data to infer root phenotypes. Current technologies for this technique include electromagnetic induction and neutron moisture meters; however, ground penetrating radar (GPR) has been proven to measure soil water content at varying depths by detecting subsurface anomalies with different dielectric permittivities. The objective of this study is to use GPR as a novel technique for detecting roots and classifying root phenotypes based on the detection of differences in dielectric permittivity in response to changes in soil water content. The study will be conducted at three sites: a Burleson clay with three root types, an Amarillo fine sandy loam with three root types, and a site with variable soil types with a single root type. Data will be collected along a linear transect in each plot with a PulseEkko GPR bi-static unit operating at a radio frequency of 500 MHz. Additionally, an EM38-MK2 survey will be performed and neutron moisture meter readings will be collected to correlate and verify the GPR data. Readings will be taken throughout the summer during the dry down to monitor the changes in soil moisture. The ability of GPR to distinguish root types across soils will be assessed.