Phenotyping the Future Crops: the Potential of Electrical Imaging (Invited): NS35B-0358

A key pathway to maximize yields in a sustainable way is to select and grow crops that are optimally adapted to their environment. Plant performance is controlled by characteristics or ‘traits’ which are partially genetically determined. Nevertheless, cultivars with the same genome (G) express different appearances in different environments (E) and under different management practices (M). Phenotyping has therefore become the foundation of breeding practice. Above-ground traits are already extensively studied in lab and field. Phenotyping the below-ground traits is less straightforward, due to the opaque nature of soil. Non-invasive geophysical techniques to study the root system and soil profile have substantially advanced in recent years. Their biggest potential lies in their indirect monitoring of water depletion or other changes in the root zone. Timelapse electrical resistivity tomography (ERT) is particularly promising as part of a comprehensive field phenotyping installation. Nevertheless, it remains unclear whether the technique can deliver the resolution, sensitivity and accuracy to capture the subtle, but decisive differences between cultivars.
In this study, we simulated a range of possible continuous ERT measurement setups and tested them for their potential to distinguish between small differences in below-ground dynamic plant traits of grass. A combination of surface and subsurface electrodes proves thereby indispensable and the electrode spacing should be sufficiently small. Nevertheless, a lot of uncertainty remains in field conditions due to the heterogeneous nature of soil and plant processes in space and time. Some can be alleviated by careful site characterization (eg. heterogeneity of hydraulic characteristics) and independent measurements of influencing factors (eg. temperature, salinity, soil moisture). Others are inherent to the method and need to be taken into account during data interpretation. The technique is currently being implemented in a unique field phenotyping installation as a part of the European phenotyping network EMPHASIS.