Reflectance characteristics of maize and application of vegetation indices for estimation of leaf area index

Abstract

An experiment was conducted on maize (Zea mays L), grown as a fodder crop, under irrigated and partially irrigated conditions with Ground Truth Radiometer at the experimental farm of the College of Agriculture, Pune under Mahatma Phule Krishi Vidyapith, Rahuri during pre-kharif season of 1999. Observations were taken at weekly intervals between 1000 and 1100 hrs. (IST) on cloud free days during the crop growing season. The spectral radiance characteristics and vegetation indices like Normalized Difference Vegetation Index (NDVI), Ratio Vegetation Index (RVI), Weighted Difference Vegetation Index (WDVI), Perpendicular Vegetation Index (PVI) and their relationship with Leaf Area Index (LAI) have been studied. The paper discusses the significance of spectral variation of radiance and sensitivity of vegetation indices with respect to phenological stages of the crop. The spectral reflectance observations in red and near infrared bands were recorded from the crop field. Vegetation indices were found suitable for crop growth studies. The procedure for estimating LAI using different vegetation indices is also discussed in the paper. It has been found that RVI is a better predictor of LAI during the early stage of growth while NDVI is a better predictor during the later part of growth as compared to other vegetation indices.