Sensitivity of hyperspectral bands to N concentration at different growth stages in winter wheat

Spectral indices are a precision tool to increase nutrient use efficiency by estimating N crop status. In this study, canopy hyperspectral reflectance (325 -1075 nm) were recorded at three different growth stages of winter wheat in two years.

The objective was to assess the sensitivity of all possible two-bands (λ) combination in a normalized difference spectral index [NDSI(λ1, λ2) = (λ1-λ2)/(λ1+λ2)] to crop N concentration at different growth stages. The results indicated that NDSI(NIR, Red-Edge) and NDSI(510, 450) were the most accurate indices to determine %N. Due to the early estimation, they could be used to adjust N fertilization.