We analyzed reflectance spectra acquired between 400 and 1000 nm at fine spectral resolution on potato fields subjected to two different irrigation regimes and four nitrogen (N) fertlization rates. Hyperspectral reflectances were shown to be suitable for discriminating between the N treatments, the difference between treatments being stronger for the non-irrigated plots than for the irrigared plots. A hyperspectral index ρ_(667)/ρ_(717) has been proposed, which gave the highest correlation with canopy biological variables, like biomass, N and chlorophyll content and ground cover. However, it was less correlated to leaf-level variables, like N and chlorophyll concentration and petiole nitrate than the SPAD leaf chlorophyll index and λ_0. Whatever the level, the red-edge inflection point (λ_(RE)) was poorly correlated to the biological variables. There is the need to calibrate more complex models to retrieve leaf variables from the canopy reflectance spectra.
展开▼
