The effect of diameter variation on root elongation, branching and topological connections has not been examined systematically in a population of high-order roots, nor along the roots.
Wu et al. used very detailed information on the geometry and topology of the root system of field-grown maize to study the relationships between root diameter and other root architectural characteristics. The final length of a lateral root was associated with the size of the basal root and the extent of diameter change along the root, and the branching density of laterals was determined by the diameter and the positions of the bearing segment.
Qian Wu, Loïc Pagès, Jie Wu, 2016, 'Relationships between root diameter, root length and root branching along lateral roots in adult, field-grown maize', Annals of Botany, vol. 117, no. 3, pp. 379-390 http://dx.doi.org/10.1093/aob/mcv185