Improving winter wheat yield prediction by novel spectral index

The coefficients of correlation between yields and spectral reflectances in eight different growth stages were first calculated. The statistical results show that yield is positively correlative with spectral reflectance in NIR bands for all the growth stages, negatively correlative in visible bands from late jointing stage, and also negative correlative in shortwave-infrared bands from seeding stage. Second, the normalized difference spectral indices combined by ［890 nm, 1200 nm］, ［890 nm, 980 nm］, ［890 nm, 1650 nm］, ［890 nm, 1650 nm］ and ［890 nm, 2200 nm］ are significantly correlative with yields in all the 8 growth stages, which is better than NDVI. Finnally, the remote sensing models in different growth stages for winter wheat yield were built by ［890 nm, 1650 nm］ weak water absorption index.