Multi-Channel Spectral Sensors as Plant Reflectance Measuring Devices—Toward the Usability of Spectral Sensors for Phenotyping of Sweet Basil (Ocimum basilicum)

Abstract

Modern agriculture demands for comprehensive information about the plants themselves. Conventional chemistry-based analytical methods—due to their low throughput and high associated costs—are no longer capable of providing these data. In recent years, remote reflectance-based characterisation has become one of the most promising solutions for rapid assessments of plant attributes. However, in many cases, expensive equipment is required because accurate quantifications need assessments of the full reflectance spectrum. In this experimental study, we examined the versatility of visible spectral sensors as alternative reflectance measuring devices for biological/biochemical quantifications of sweet basil (Ocimum basilicum). Our results confirm the applicability and scope of visible spectral sensors for analysis and quantification of important plant properties, in particular the contents of valuable substances, such as phenolic compounds and flavonoids.

Determining the Nutrient Content of Hydroponically-Cultivated Microgreens with Immersible Silicon Photonic Sensors: A Preliminary Feasibility Study

“…Interestingly, this downward trend aligns with the findings from the Folin-Ciocalteu assay, hinting at a potential link between the sensor signal and the total phenolic content of basil microgreens. However, it is important to note that this study was limited in breadth, and that further investigations are required to validate this hypothesis, as was explained in the recent report by Tran et al [30] that employed spectral multi-channel spectral sensors as plant reflectance measuring devices to determine the total phenolic content of basil. A more comprehensive exploration would involve a larger set of experiments conducted across multiple generations of hydroponically cultivated crops.…”

“…This study explores an alternative method for determining the nutrient content of microgreens by using hydroponically grown basil microgreens as a test case. In contrast to recent approaches that use light to determine the nutrient content of soil or plants through spectroscopic methods, such as FT-IR, TXRF, and UV/VIS [23][24][25][26][27], color analysis [28,29], or spectral imaging [30], the proposed approach uses "light" and spectroscopic analysis in a different way. It employs a novel type of immersible Si-based photonic sensor using Broad-band Mach-Zehnder Interferometry (BB-MZIs) as the principle of operation [31][32][33].…”