VEGETATION INDICES AND THEIR CORRELATION WITH SECOND-CROP CORN GRAIN YIELD IN MATO GROSSO DO SUL, BRAZIL

The emergence of satellites covering new electromagnetic wavelengthsallowed developing different vegetation indices, enabling the study of theircorrelation with grain yield. In this sense, this study aimed to evaluate the accuracy between the mean values of seven vegetation indices and the mean corn grain yield in the field by applying linear regression equations. The indices NDVI, NDRE, GNDVI, GRNDVI, and PNDVI were used, with changes proposed in the equations of the indices GRNDVI and PNDVI, in which the red wavelength was replaced by the red edge. The multispectral bands provided by the Sentinel-2A and Sentinel-2B imaging instruments were used as a source of data to calculate the vegetation indices, while the values recorded by the grain harvester were used for the survey of grain yield data. A high correlation was observed between indices and grain yield. The replacement of the red wavelength with the red edge improves the correlation between vegetation indices and grain yield. Moreover, the indices GNDVI and NDVI easily saturate, reaching maximum values and not allowing the distinction between sample classes. Therefore, the vegetation indices PRENDVI and GRENDVI are recommended for estimating grain yield.