NUTRITIONAL STATUS OF CORN PLANTS ESTIMATED THROUGH DIFFERENT VEGETATION INDICES IN THE GROWTH STAGES

Abstract

Several vegetation indices (VIs) have been proposed in the literature with the objective of exploring the spectral properties of the vegetation as they are usually related to biophysical parameters of the plants. The objective of this study was to evaluate the relationship between VIs, obtained in two different RPAS platforms (Remotely-piloted spacecraft system) and proximity system at different corm growth stages with the nitrogen (N) nutritional status in the plant. Five treatments with different nitrogen fertilizer rates (20, 60, 120, 180 and 240 kg ha-1) were studied in order to generate the variability of nitrogen uptake by the plant in four blocks with five replicates each. Reading of the following VIs were performed: NDRE and NDVI (proximity sensing, Optrix sensor) and NDRE, NDVI, EVI2 and GNDVI (RPAS platform, MicaSense Parrot Sequoia sensor) at the phenological stages V5, V6, V7, V9, V11 and V12. Corn plants were collected to evaluate N content in the aerial part of the plant. The N content was higher in V7 growth stage and lower in V12 stage. The VIs obtained through the RPAS platform presented higher relationship with the corn nutritional status when compared to the proximity sensors. The V12 corn growth stage had higher relationship of VIs and plant N content in comparison to the proximity sensor.