Correlative analyses of hyperspectral reflectance, soybean LAI and aboveground biomass

Canopy reflectances of soybean were measured with ASD FieldSpec during different growth stages; and simultaneously, LAI and biomass were acquired. The relationships between canopy reflectance, derivative and LAI, biomass were analyzed with every single band. Determination coefficient (R²) was obtained with linear regression of soybean reflectance and derivative against LAI and biomass. Different regression models were applied to establish the relationship between RVI and soybean LAI and biomass. It is found that soybean canopy reflectance has an intimate relationship with soybean LAI, biomass in visible spectral region 350～680 nm and near infrared spectral region 760～1050 nm while the relationship between reflectance and soybean LAI, biomass has a loose relation in red edge spectral region at different growth stages; for derivative, the relationship shows an inverse trend, it has an close relationship between derivative and soybean LAI, biomass in red edge spectral region, but in visible spectral region 350～680 nm and near infrared spectral region 760～1050 nm, this is not the case for that with soybean canopy reflectance. The study shows that RVI model constructed by hyperspectral remote sensing reflectance from near infrared spectral region and visible spectral region regressing against soybean LAI, biomass with power functions and exponential functions can greatly improve remote sensing ability for estimating soybean LAI, biomass.