Predicting grain yield and protein content using canopy reflectance in maize grown under different water and nitrogen levels

•This work estimates maize grain yield and protein using physiological parameters.•Water and nitrogen availability affect maize grain yield and protein content.•Physiological parameters of maize are estimated using RVI and wavelet methods.•Maize productivity model integrates canopy spectra and physiological parameters.•The results are promising for the operational estimation of maize production.