Optical Photoluminescent Properties of Plant Seeds when Infected with Mycopathogens

Abstract

Introduction. Using digital technologies such as optical monitoring of grain quality will reduce losses of grain crops caused by infection with mycopathogens. Aim of the Study. The study is aimed at investigating spectral characteristics, excitation parameters and luminescence of cereal seeds when infected with mycopathogens to determine informative spectral ranges and subsequent development of infection control methods. Materials and Methods. In the study, there were used wheat and barley seeds inoculated with Fusarium graminearum, Alternaria alternata. Excitation and luminescence registra- tion spectra were measured by a diffraction spectrofluorimeter CM 2203 in the range of 230–600 nm. Integral and statistical parameters of spectra were calculated with the use of Microcal Origin program. Results. It was found that the spectral absorbency of seeds decreases when infected with mycopathogens. For wheat, the integral absorption parameters decrease more significantly when infected with alternaria, and for barley, on the contrary, a greater decrease occurs when infected with fusarium. In the area of 230–310 nm, new excitation maxima appear in infected seeds. When excited by radiation with a wavelength of λ = 284 nm, the spectral and integral characteristics and parameters of infected seeds exceed those for uninfected ones. When excited with 424 nm and 485 nm radiation, the number of disease-free seeds of both wheat and barley exceeds the number of infected seeds. Discussion and Conclusion. The changes in excitation and photoluminescence spectra can be explained by the substitution of polysaccharides and proteins during mycoculture uptake and modification. To objectively monitor the mycopathogen infestation of seeds, it is advisable to use a photoluminescence range of 290–310 nm when excited by radiation of about 284 nm. To determine if the infection caused with fusarium or alternariasis, photoluminescence monitoring should be used in the range of 380–410 nm.