Spectral reflectance characteristics, vegetation and leaf area indices for sorghum (Sorghum bicolor L.)

Abstract

A growing number of studies have focused on evaluating the spectral indices in terms of their sensitivity to vegetation biophysical parameters like leaf area index. In this context, different hyperspectral ratios and normalized difference vegetation indices were computed for sorghum based on groundbased spectral data obtained in 350-2500 nm wave length region over the crop growth period of sorghum. The analysis of the hyperspectral data was carried out to compare the performance of vegetation indices (Normalized Difference Vegetation Index [NDVI], Renormalized Difference Vegetation Index [RDVI], Modified Simple Ratio [MSR], Soil-Adjusted Vegetation Index [SAVI], Modified Soil-Adjusted Vegetation Index [MSAVI], and Modified Chlorophyll Absorption Ratio Index [MCARI]) by linearly relating to LAI separately for growth and decline phases. The regression coefficient values were found in the range of 0.79 to 0.87 for growth phase and 0.89 to 0.98 for decline phase. The most significant relationship of LAI was found with MSAVI when growth (R2 of 0.87) and decline (R2 of 0.98) phases were analyzed separately