Ndvi Modis Sensor Response to Soybean Phenology in the State of Parana, Brazil

This study aimed to evaluate the response of the Normalized Difference Vegetation Index NDVI derived from Terra MODIS sensor to soybean phenology, in a grain producer region of Parana State, Brazil. Landsat TM and ETM+ images were selected to analyze the spatial distribution of soybean fields for this region from 2000/01 to 2006/07 crop seasons. Then pure pixel samples (250 x 250m) that contained only soybean fields were identified in three locations, based on previously obtained maps from Landsat TM images. The next step was to extract NDVI MODIS values for these soybean pure-pixels and to analyze the NDVI spectral curves considering the soybean phenology for all locations. Several pixels were inspected in order to ensure that a reduction in NDVI values was not caused by the presence of clouds. NDVI values adequately described the soybean phenology, showing soybean growing season (November to March) and the dry season for this region, for all locations in study region.