A Novel Method for Estimating Chlorophyll and Carotenoid Concentrations in Leaves: A Two Hyperspectral Sensor Approach

Abstract

Leaf optical properties can be used to identify environmental conditions, the effect of light intensities, plant hormone levels, pigment concentrations, and cellular structures. However, the reflectance factors can affect the accuracy of predictions for chlorophyll and carotenoid concentrations. In this study, we tested the hypothesis that technology using two hyperspectral sensors for both reflectance and absorbance data would result in more accurate predictions of absorbance spectra. Our findings indicated that the green/yellow regions (500–600 nm) had a greater impact on photosynthetic pigment predictions, while the blue (440–485 nm) and red (626–700 nm) regions had a minor impact. Strong correlations were found between absorbance (R2 = 0.87 and 0.91) and reflectance (R2 = 0.80 and 0.78) for chlorophyll and carotenoids, respectively. Carotenoids showed particularly high and significant correlation coefficients using the partial least squares regression (PLSR) method (R2C = 0.91, R2cv = 0.85, and R2P = 0.90) when associated with hyperspectral absorbance data. Our hypothesis was supported, and these results demonstrate the effectiveness of using two hyperspectral sensors for optical leaf profile analysis and predicting the concentration of photosynthetic pigments using multivariate statistical methods. This method for two sensors is more efficient and shows better results compared to traditional single sensor techniques for measuring chloroplast changes and pigment phenotyping in plants.

Simultaneous Quantification and Visualization of Photosynthetic Pigments in Lycopersicon esculentum Mill. under Different Levels of Nitrogen Application with Visible-Near Infrared Hyperspectral Imaging Technology

“…In the visible spectral region, Chla, Chlb and Chls mainly absorb blue, purple and red light, with two strong absorption regions at 400–460 nm and 630–680 nm [ 5 , 8 , 31 , 32 ]. Cars mainly absorbs blue and purple light, which is a strong absorption region at 400–500 nm [ 5 , 10 , 33 , 34 ]. In the near-infrared spectral region, it is mainly caused by the absorption of water or oxygen.…”

Hyperspectral and Chlorophyll Fluorescence Analyses of Comparative Leaf Surfaces Reveal Cellular Influences on Leaf Optical Properties in Tradescantia Plants

“…The interaction of cells in leaves with reflectance (R) and transmittance (T) properties in vivo was measured quantitatively using a novel method developed by Falcioni et al (2023) [ 2 ] with a FieldSpec ® 3 spectroradiometer from Analytical Spectral Devices (ASD), Inc., Longmont, CO, USA [ 31 , 32 , 33 ]. This instrument, coupled with an ASD Contact PlantProbe ® (ASD Inc., Longmont, CO, USA) with 10 mm diameter, features a sophisticated detector array consisting of 512 InGaAs photodiodes, enabling highly accurate spectral data collection from 350 to 2500 nm.…”

“…The sensor settings were adjusted to 1000 and 1800 nm using the ViewSpec Pro software version 6.2 (ASD Inc., Boulder, CO, USA). In addition, this study also included data on spectral curves and leaf pigments assessed under in vitro conditions, covering the wavelength range of 350–750 nm [ 31 , 32 , 33 ].…”

Chemometric Analysis for the Prediction of Biochemical Compounds in Leaves Using UV-VIS-NIR-SWIR Hyperspectroscopy

“…The marked difference in reflectance values, as corroborated by the t test, underscores the intrinsic biochemical variance between Hibiscus and Geranium. These differences may be attributed to variations in the chlorophyll content, cellular structures, and moisture content [31].…”