Relationship between biophysical parameters and Normalized Difference Vegetation Index in maize

A field experiment was conducted for two years during kharif season at ARI farm, Rajendranagar, Hyderabad to study the spectral reflectance pattern of maize crop and its relationship with biophysical parameters like Leaf Area Index (LAI), stover yield and grain yield. The experiment was laid out in RBD (Factorial) with three replications. The treatments comprised of four dates of sowing and four irrigation regimes. The spectral characteristics of the crop were measured at weekly intervals using a hand-held, multiband ground truth radiometer. In all dates of sowing, rainfed (moisture-stressed) crop showed lower Normalized Difference Vegetation Index (NDVI) values than irrigated crop throughout crop growing season. The NDVI and LAI are related exponentially and the predicted values of LAI are in good agreement with observed values. The integrated NDVI of different treatments was computed and significant correlation was found between integrated NDVI and, stover yield and grain yield. The result indicates that the grain yield can be estimated using satellite image derived NDVI in large areas. The relationship was found to be logarithmic during pre NDVImax and was linear during post NDVImax period.