Influence of the direction of the corn sowing in its reflectance in the 550-nm band and in the green normalized difference vegetation index

The objective of this work was to study the influence of the direction of the corn sowing in its reflectance and in the Green Normalized Difference Vegetation Index - GNDVI, seeking to supply necessary information to make possible a system of located application of nitrogen (N) in real time. The corn was sowed being used the technique of the direct planting, being administered the nutrients in agreement with the soil need and with a constant N rate of 160 kg/ha. The sowing lines were located in the North-South (NS) and East-West (EW) directions. It can be concluded that the corn sowed at EW presented smaller reflectance and GNDVI and they were less dependent of the time than the corn sowed at NS. The GNVI showed more interesting appropriate for use in real-time variable-rate application system for N fertilizer based on canopy reflectance for showing less sensitive the sowing direction.