Spectral radiance Characteristics and Vegetation Indices of Selected Rabi Crops

The feasibility of differentiating three Rabi crops viz., wheat, potato and sunflower, based on their spectral reflectance in the red and infrared region was studied in the crop season of the year 1998–99. The spectral indices like Simple Difference Index (SDI), Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI) and Perpendicular Vegetation Index (PVI) were computed from spectral reflectance measurements to identify the most sensitive vegetation index as an indicator of growth of these crops. The results indicate that: Crop canopy on an average reflects about 10 per cent of red radiation and 70 per cent of infrared radiations and thus red and infrared are the two most important regions which provide valuable information about the vigour status of the crop canopy; PVI is the most sensitive index followed by RVI and NDVI for differentiation of crops under consideration.