Exploring the utility of Sentinel-2 data for the retrieval of the leaf area index of maize across different growth stages

This study investigated the utility of Sentinel-2 spectral data for estimating the leaf area index (LAI), and the leaf and canopy chlorophyll content of maize at different growth stages. Vegetation indices based on the visible–near infrared and red-edge regions of the spectrum were computed from Sentinel-2 imagery acquired within one or two days of field data collection. Results showed that the green chlorophyll index (CI_green) and red-edge chlorophyll index (CI_red-edge)_, using the red-edge variant centred at 705 nm, consistently showed a stronger relationship with maize LAI with r² values of 0.65 and 0.63 during the early stages of growth, respectively, and r² values of 0.79 and 0.81 during the tassel stage, respectively. Regarding canopy chlorophyll content, the results indicated the spectral advantage of the Sentinel-2 sensor with the presence of two red-edge bands for the continuous monitoring of maize chlorophyll content. Overall, the study results indicated that maize biophysical variables can be monitored at the satellite level and with acceptable accuracy when using Sentinel-2 data.