Estimating flavonoids using radiative transfer model inversion on imaging spectroscopy data

Abstract

Assessing flavonoid content is crucial for understanding plant responses to biotic and abiotic stresses. However, pigments such as chlorophylls, carotenoids, and anthocyanins, absorb light between 410 and 430 nm, thus makes it difficult to quantify flavonoid content in this region. To improve the sensitivity of flavonoids have been developed, but they are largely empirical and lack transferability across environments. Therefore, this study compares the effectiveness of the PROSAIL-D radiative transfer model (RTM) and an empirical approach in mapping flavonoids using AVIRIS data in the Fynbos biome through indices. Results show that PROSAIL-D consistently outperformed the empirical method, with the spectral index FI 417,693 achieving an R 2 of 0.63 and RMSE of 0.24 (mg catechin (CAE)/g). The empirical approach with the same index yielded an R 2 of 0.46 and RMSE of 5.11 mg CAE/g. Overall, the RTM model demonstrated superior accuracy, with RMSE values ranging from 0.24 to 1.70, compared to 5.11 to 6.28 for empirical methods. These findings highlight the potential of integrating AVIRIS data with PROSAIL for non-destructive, remote sensing-based assessment of flavonoids, offering a scalable approach for monitoring plant health and stress responses at the canopy level.