Effects of Coating on Seed Imbibition: I. Model Estimates of Water Transport Coefficient

Abstract

Seed coatings are used to facilitate local applications of products, including systemic chemicals. However, they may slow imbibition, the rate of which will probably further decrease with multi‐layer coatings. In this paper, we propose a method based on the use of a simplified model for estimating of the hydraulic conductivity and vapor diffusion coefficient of seed coatings as a function of seed water content. This method results from theoretical calculations established for spherical systems having only an external resistance to water transport. Extension of these calculations to systems in which the internal resistance to water transport may not be neglected was checked with a onedimensional spherical mechanistic model of seed imbibition. Using a numerical method, we simulated imbibition for seeds in liquid water with the mechanistic model. These simulation results were analyzed, thereafter, by the simplified model. Whatever the ‘seed‐coating’ system of interest, it was always possible to simulate imbibition with the simple model without introducing a bias larger than 3% of the average seed water content. When seed resistance was negligible compared with coating resistance, the estimate of the coating hydraulic conductivity as a function of the water content was nearly equal to the theoretical conductivity. If the seed resistance was large, relative to the coating resistance, estimates of this relationship were possible if imbibltion data were available for different levels of seed coating. In the studied situations, the method led to a bias contained within a 1 to 25% range for the conductivity of the coating.