A new methodology to characterize the kinetics of a seed during the imbibition process

Abstract

Aims Assuming the saturated, θs, and residual θr volumetric water contents of a seed as known inputs, we present a methodology to determine the hydraulic properties of a seed: α, n parameters and hydraulic conductivity Ks. Methods The seed is considered as a porous material in which water flow is governed with the same hydraulic properties defined for soils. Using the HYDRUS-2D software, the hydraulic properties of a seed were estimated from the inverse analysis of several cumulative seed imbibition curves measured at different seed water potentials, h. The optimum number of h was evaluated on synthetic seeds. The theoretical analysis was validated in laboratory experiments on barley, wheat and vetch seeds, where imbibition curves were measured with germination tests at seven levels of h (from 0 to -2.50 MPa). Results The theoretical analysis showed that accurate estimates of α, n and Ks can be obtained if the most negative h-values are included in the optimization. The sensitivity analysis showed that the method allows obtaining a unique solution of α, n and Ks. The optimization error on the theoretical α, n and Ks was less than 1%. A satisfactory validation was also obtained on the experimental seed imbibition curves, with robust fits between the measured and optimized data. A unique solution of α, n and Ks was also obtained in all cases. Conclusions A new method to determine the hydraulic properties of a seed is presented. This methodology could be used in different areas involving seed imbibition and also to simulate seed imbibition in different scenarios.