Developing a New Vegetation Index Using Cyan, Orange, and Near Infrared Bands to Analyze Soybean Growth Dynamics

Abstract

Remote sensing Vegetation Indices (VIs) are simple, effective, and widely used methods for quantitative and qualitative analysis of vegetation cover, vigor, and growth dynamics. This study developed and assessed a new vegetation index (VI) using Cyan, Orange, and Near Infrared (NIR) bands to assess Soybean growth dynamics. The study was conducted at Lakehead University Agriculture Research Station, Thunder Bay, Canada, over four reproductive stages of Soybean growth (R4–R7). Spectral profiles were created for each stage, and the correlation between each spectral band at different stages was tested. There was no linear correlation between different bands except the correlation between the Cyan and Orange bands at R5 and R6 stages. Existing VIs have also been explored using approximately similar band combinations. Based on this analysis, three VIs were proposed for this new camera, and their behavior at different stages was evaluated using Leaf Area Index (LAI). Cyan and Orange spectral values were relatively high in the first and last growing seasons, while NIR values increased dramatically in the mid-growing seasons and decreased in the last stage. VINIR,O,C index showed the best results for mid-growing seasons (correlation with LAI = 0.39 for R5 and R6). VIC,O index showed a high level of details visually (leaves and background) for R4 and R7 than the other indices and correlated highly with LAI (0.48 and −0.5, respectively). Overall, the study provided new VIs that can be used to effectively analyze Soybean growth dynamics, with different VIs showing reliability over different growing stages.