# Preferential Root Tropism Induced by Structural Inhomogeneities in 2D Wet Granular Media

## TL;DR

This study explores how structural inhomogeneities in 2D granular media influence root growth by redistributing water, leading to preferential tropism that enhances water access and plant longevity.

## Contribution

It demonstrates that solid intrusions can induce water redistribution and root tropism, revealing a physical mechanism for root adaptation in granular media.

## Key findings

- Roots grow preferentially towards water-rich regions near inhomogeneities.
- Structural intrusions maintain capillary action, aiding water redistribution.
- Root growth is enhanced, increasing plant lifetime.

## Abstract

We investigate certain aspects of the physical mechanisms of root growth in a granular medium and how these roots adapt to changes in water distribution induced by the presence of structural inhomogeneities in the form of solid intrusions. Physical intrusions such as a square rod added into the 2D granular medium modify water distribution by maintaining robust capillary action, pumping water from the more saturated areas at the bottom of the cell towards the less saturated areas near the top of the cell while the rest of the medium is slowly devoid of water via evaporation. This water redistribution induces `preferential tropism' of roots, guiding the roots and permitting them to grow deeper into more saturated regions in the soil. This further allows more efficient access to available water in the deeper sections of the medium thereby resulting to increased plant lifetime