Field hyperspectral imagery as a tool for plant monitoring: application to wheat nitrogen content

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIREInternational audienceIn the study presented here, we used a pushbroom CCD camera fitted on a motorised tractor rail to take hyperspectral images of wheat plots. Reflectance correction was performed using a ceramic plate as a reference. The hyperspectral images have been used to build nitrogen (N) content images for wheat plots using two Partial Least Square regression models. The first chemometrical model was calibrated on nitrogen contents (in percentage of dry matter, % DM) obtained in laboratory and flat leaf normalised spectra (5 latent variables, R² = 0.907, RMSEP = 0.326 N % DM); the second one on greenhouse pot plant leaf spectra (8 latent variables, R² = 0.919, RMSEP = 0.412 N % DM). Subsequently, they were directly applied to field plant spectra, providing images of nitrogen content. The range of nitrogen content values in these images was not satisfactory. Due to important spectral differences between greenhouse pot plant leaf spectra and field leaf spectra, a model calibrated directly on field leaves is necessary