The shape of the root system creates a lot of the context for plants to interact with a source of nutrients, water and pathogens. If you can characterize root system architecture, then you can investigate root functions and interactions. However, examining this is difficult, partly for the obvious reason that soil is difficult to see through, but also because root systems are plastic (in this meaning, easily changeable and reformed).
To examine root systems, Loïc Pagès and Jocelyne Kervella examined roots of 60 species growing in natura and measured them against five traits:
- extreme tip diameters (Dmin and Dmax)
- relative diameter range (Drange)
- mean inter-branch distance (IBD)
- dominance slope between the diameters of parent and lateral roots (DlDm).
They picked the plants from two contrasting locations to see what might be due to genetics and what could be the result of environment.
Pagès, L. and Kervella, J. (2018). Seeking stable traits to characterize the root system architecture. Study on 60 species located at two sites in natura. Annals of Botany. https://doi.org/10.1093/aob/mcy061