In connection with the constant growth of demand for high-quality food products, there is a need to develop effective methods for storing agricultural products, and the registration and predicting infection in the early stages. The studying of the physical properties of infected plants and seeds has fundamental importance for determining crop losses, conducting a survey of diseases, and assessing the effectiveness of their control (assessment of the resistance of crops and varieties, the effect of fungicides, etc.). Presently, photoluminescent methods for diagnosing seeds in the ultraviolet and visible ranges have not been studied. For research, seeds of winter wheat were selected, and were infected with one of the most common and dangerous diseases for plants—fusarium. The research of luminescence was carried out based on a hardware–software complex consisting of a multifunctional spectrofluorometer “Fluorat-02-Panorama”, a computer with software “Panorama Pro” installed, and an external camera for the samples under study. Spectra were obtained with a diagnostic range of winter wheat seeds of 220–400 nm. Based on the results obtained for winter wheat seeds, it is possible to further develop a method for determining the degree of fusarium infection.
At present, one of the critical problems in agriculture is the identification of cereals, including oats, infected by Fusarium spp. genus fungi. Timely diagnostics can prevent the further disease spread and help to identify the already stored infected grains. In this regard, the aim of this work is to develop the spectroscopic approaches that determine the infected grains. As an object of the investigation the “Zalp” cultivar oat, both healthy and infected grains of the 2020 harvest were chosen. The spectroscopic diagnostics included FTIR in the mid-IR region, Raman, and luminescence methods. Combination of chemometric tools with FTIR and Raman spectroscopy allowed obtaining approaches based on identified characteristic spectral features which may be used as infection markers. These approaches make it possible to detect the infection on the grain husk. The carotenoid type fungi pigment was identified within the resonance conditions of Raman scattering excitation. The luminescence study of infected oat husk revealed the presence of characteristic chlorophyll α peak which is absent in healthy grain husk.
This paper discusses the applicability of optical and vibrational spectroscopies for the identification and characterization of the T-2 mycotoxin. Vibrational states and electronic structure of the T-2 toxin molecules are simulated using a density-functional quantum-mechanical approach. A numerical experiment aimed at comparing the predicted structural, vibrational and electronic properties of the T-2 toxin with analogous characteristics of the structurally similar 3-deacetylcalonectrin is performed, and the characteristic spectral features that can be used as fingerprints of the T-2 toxin are determined. It is shown that theoretical studies of the structure and spectroscopic features of trichothecene molecules facilitate the development of methods for the detection and characterization of the metabolites.
The development and application of optical luminescent methods and devices will help obtain information quickly and objectively about the level of Fusarium infection of agricultural plants. For the previously obtained ranges, the spectral characteristics of excitation and luminescence of wheat, barley, and oats of various degrees of infection were measured. The obtained dependences of flows on infection were approximated by linear regression models and relative sensitivities were determined. For wheat and barley, it is advisable to determine the degree of infection by the ratio of flows Φλ1/Φλ2, which makes it possible to calibrate the measuring device in relative units and increase its sensitivity. A method for determining the degree of infected seeds with Fusarium was developed. After the seeds are placed in a light-tight chamber, they are excited by radiation, and photoluminescence is recorded. The electrical signal from the radiation receiver is amplified and processed accounting for previously obtained calibration curves. In the universal device that measures the infection of wheat, barley, and oats seeds, it is necessary to have three radiation sources: 362 nm, 424 nm, and 485 nm. Based on the energy efficiency criteria, optimal LEDs and photodiodes, as well as a microcontroller, switches, operational amplifiers, a display, and other components of the device, were selected.
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