Imbibition in plant seeds

TL;DR

This study combines experiments and theory to analyze imbibition in plant seeds, demonstrating that capillary action governs moisture uptake and modeling the wet front's evolution over time.

Contribution

It introduces a capillary-based model that accurately predicts the imbibition dynamics in both natural and artificial seeds, validated by experimental data.

Findings

Liquid permeates seeds at decreasing rates over time.

The wet front follows a $t^{1/2}$ growth initially, then scales as $(1-t/t_{max})^{1/2}$.

Experimental data aligns with the capillary model, indicating capillary action's role in seed imbibition.

Abstract

We describe imbibition in real and artificial plant seeds, using a combination of experiments and theory. In both systems, our experiments demonstrate that liquid permeates the substrate at a rate which decreases gradually over time. Tomographic imaging of soy seeds is used to confirmed this by observation of the permeating liquid using an iodine stain. To rationalize the experimental data, we propose a model based on capillary action which predicts the temporal evolution of the radius of the wet front and the seed mass. The depth of the wetting front initially evolves as $t^{1/2}$ in accord with the Lucas-Washburn law. At later times, when the sphere is almost completely filled, the front radius scales as $(1-t/t_{\text{max}})^{1/2}$ where $t_{\text{max}}$ is the time required to complete imbibition. The data obtained on both natural and artificial seeds collapse onto a single curve that agrees well with our model, suggesting that capillary phenomena contribute to moisture uptake in soy seeds.