Correlation of NDVI Obtained by Different Methodologies of Spectral Data Collection in a Commercial Crop of Quinoa (Chenopodium Quinoa) in Central Ecuador

The current study relates the normalized difference vegetation index (NDVI) of a variety of methodologies of quinoa in a controlled experiment and a commercial crop, with airborne multispectral sensor and a spectroradiometer. Hereby, an unmanned aerial vehicles (UAV) flight has been realized, obtaining the NDVI indexes values as well as spectral signatures. Correlation has been performed between the NDVI values obtained with the spectroradiometer (NDVI_E), from the automatically generated raster (NDVI₁) and from the Red and NIR ortho-mosaics (NDVI2). Hereby, the value of R2 of NDVI_E vs. NDVI₁ indicates a negative correlation in the data. The data yielded, that this is due to the fact that the NDVI₁ map did not perform an orthorectification, due to the difficulty in identifying control points. In the case of the NDVI_E vs. correlation of NDVI₂, the value of R2 has been very low, allowing only a weak correlation. Preliminarily, the use of NDVI in plants that do not reach a high plant density is not feasible, due to the influence of the soil, what is reflected in the given values.