Root Circumnutation Reduces Mechanical Resistance to Soil Penetration

Abstract

Root circumnutation, the helical movement of growing root tips, is a widely observed behaviour of plants. However, our mechanistic understanding of the impacts of root circumnutation on root growth and soil exploration is limited. Here, we deployed a unique combination of penetrometer measurements, X-ray computed tomography and time-lapse imaging, and cavity expansion modelling to unveil the effects of root circumnutation on the mechanical resistance to soil penetration. To simulate differences in circumnutation amplitude and frequency occurring among plant species, genotypes and environmental conditions, we inserted cone penetrometers with varying bending stiffness into soil samples that were subjected to orbital movement at different velocities. We show that greater circumnutation intensity, determined by a greater circumnutation frequency in conjunction with a larger circumnutation amplitude, decreased the mechanical resistance to soil penetration. Cavity expansion theory and X-ray computed tomography provided evidence that increased circumnutation intensity reduces friction at the cone-soil interface, indicating a link between root circumnutation and the ability of plants to overcome mechanical constraints to root growth. We conclude that circumnutation is a key component of root foraging behaviour and propose that genotypic differences in circumnutation intensity can be leveraged to adapt crops to soils with greater mechanical resistance.

Keywords

cavity expansion; plant movements; root analogues; soil biomechanics; soil structure; X-ray computed tomography

Published in

Plant, Cell and Environment
2024
Publisher: WILEY

SLU Authors

• Leuther, Frederic

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • University of Bayreuth

• Iseskog, Daniel

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Keller, Thomas

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Agroscope

• Larsbo, Mats

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Colombi, Tino

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • University of Nottingham

UKÄ Subject classification

Botany
Soil Science

Publication identifier

• DOI: https://doi.org/10.1111/pce.15219

Permanent link to this page (URI)

https://res.slu.se/id/publ/139241