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

Abstract

Reflectance hyperspectroscopy is recognised for its potential to elucidate biochemical changes, thereby enhancing the understanding of plant biochemistry. This study used the UV-VIS-NIR-SWIR spectral range to identify the different biochemical constituents in Hibiscus and Geranium plants. Hyperspectral vegetation indices (HVIs), principal component analysis (PCA), and correlation matrices provided in-depth insights into spectral differences. Through the application of advanced algorithms—such as PLS, VIP, iPLS-VIP, GA, RF, and CARS—the most responsive wavelengths were discerned. PLSR models consistently achieved R2 values above 0.75, presenting noteworthy predictions of 0.86 for DPPH and 0.89 for lignin. The red-edge and SWIR bands displayed strong associations with pivotal plant pigments and structural molecules, thus expanding the perspectives on leaf spectral dynamics. These findings highlight the efficacy of spectroscopy coupled with multivariate analysis in evaluating the management of biochemical compounds. A technique was introduced to measure the photosynthetic pigments and structural compounds via hyperspectroscopy across UV-VIS-NIR-SWIR, underpinned by rapid multivariate PLSR. Collectively, our results underscore the burgeoning potential of hyperspectroscopy in precision agriculture. This indicates a promising paradigm shift in plant phenotyping and biochemical evaluation.

Indirect Estimation of Heavy Metal Contamination in Rice Soil Using Spectral Techniques

“…The approach is based on the principle that heavy metals move from the soil to the plants, accumulating there [ 25 ]. Under the stress of heavy metals, the protein and chlorophyll content of the plants are affected, which leads to a discernible difference in the reflectance spectra [ 26 , 27 ]. Related research has made significant progress.…”

Estimation of Biochemical Compounds in Tradescantia Leaves Using VIS-NIR-SWIR Hyperspectral and Chlorophyll a Fluorescence Sensors

“…With the intricate cellular and foliar architecture of plants, an array of chloroplastic pigments, such as chlorophylls and carotenoids, and non-chloroplastic compounds, including anthocyanins, flavonoids, and phenolic compounds, have been identified [22][23][24]. Moreover, structural components such as lignin and cellulose play critical roles in the biomechanical integrity of plant tissues.…”

“…Moreover, structural components such as lignin and cellulose play critical roles in the biomechanical integrity of plant tissues. The concentrations of these biochemical constituents can vary significantly and are influenced by factors such as the expansion of leaf area, leaf thickness, and the number and structural alterations of cells [21,23,25]. These variations are pivotal because they reflect the biophysical and biochemical dynamics within the plant and offer insights into its adaptive responses to environmental conditions.…”

“…This choice is vital because it balances the maximisation of information retention with minimising noise. The β-loadings obtained from PCA provide a clear illustration of the spectral peaks, offering "fingerprints" of the chemical and physical properties within the dataset [22,23]. Furthermore, PCA can be combined with regression coefficients obtained from various spectral curves, such as OJIP, which represent the fluorescence kinetics over the first few seconds of illumination, and hyperspectral reflectance, transmittance, and absorbance curves.…”

“…By simplifying complex spectral data into understandable indices, HVIs enable the effective large-scale surveillance and mapping of more relevant parameters. These indices can be used to systematically identify areas of specific interest wavelengths by locating regions of interest in which key biochemical and biophysical components or fingerprint indicators show significant changes [22,23]. For example, specific HVIs can be designed to detect changes in chlorophyll content, water stress, and nutrient levels [25,29,[36][37][38].…”