Effective permittivity and scattering model for the evaluation of the leaf water status

An electromagnetic model of plant leaves at THz frequencies is presented. It allows for the determination of the leaf water status. The model bases on an effective medium theory and extends the model by Landau, Lifshitz, and Looyenga. The influence of scattering, which is dominant at higher frequencies, is described by a Rayleigh roughness factor. Results of THz time-domain spectroscopy measurements on Coffea arabica leaves are used to validate the model.