2D Kinematic Quantification of Soil Particles around Growing Plant Root based on Optical Mechanics

The quantitative kinematic description of the surrounding soil particles during root growth is a technical challenge and biologically important. In this study, a two-dimensional camera-based imaging system was used to observe micro scale interactions between plant roots and soil particles. Maize root tip was imaged during ingress into the soils. This produced a series of two-dimensional images that represent temporal resolution of the geometric soil and root configurations at the micrometer scale. These images were used as inputs for full-field kinematic quantification methods, which enabled the analysis of two-dimensional deformation of the soils around elongating root. Correlation-based discrete object tracking and contour updating were used to track the shapes and the locations of soil particles and soil aggregates, while incremental digital image correlation was proposed to extract deformation and strain field within soil particle and soil aggregate. These techniques allowed the full-field displacements and strains of the soil to be quantified and the changes in shapes of soil particles to be visualized. Experimental results show that the presented shape tracking scheme, incremental digital image correlation and the research findings will be useful for the measurement and quantification of soil particle kinematics of soil-root physical interactions.