The study of the spectral behavior of crops, through field radiometry, contributes to a better precision in models generated by remote sensing, when they are used to estimate analyze crops agronomic variables. Hyperspectral crop reflectance data are useful for several remote sensing applications in agriculture and can be transformed into vegetation indices that are related with crop biophysical parameters. There is a need for studies to define optimal wavebands to estimate crop biophysical parameters. Among the several developed indices distinguished the narrow+band normalized difference vegetation index (NB_NDVI). The aim was to analyze the NB_NDVI to estimate bean grain yield and plant height. Field canopy reflectance measurements were acquired at six bean growth stages over 48 plots with the SPECTRON SE+590 spectroradiometer. Two hundred and fifty two narrow bands between 350 and 1.100 nm with bandwidth of 2,7 nm were used. The experimental design was the randomized blocks, with split plots, with 12 treatments, 4 irrigation levels (179,5; 256,5; 357,5 e 406,2 mm) and 3 nitrogen doses (0; 80 e 160 kg ha+1), and four replicates. According to the results, the NB_NDVI were efficient to estimate plant height and grain yield. During all the crop development, the best correlations between biophysical variables and spectral variables were observed on V4 (R 2 = 0.84) and R6 (R 2 = 0.86) stages, for grain yield and plant height, respectively.Pages: 8645-865
