Application of EPR spectrometry for identifying the irradiation of wheat seeds with low-energy electrons

The study aimed to investigate the applicability of electron paramagnetic resonance (EPR) spectrometry for detecting the radiation treatment of spring wheat seeds using low-energy electrons. Seeds of the Iren variety (2023 crop, first reproduction) were irradiated one year after harvesting with electrons at energies of 100 and 120 keV over a dose range of 1…5 kGy (step 1 kGy), dose rate was 100 Gy/imp. Non-irradiated seeds served as the control. After irradiation, the seeds were stored in the dark at room temperature and relative humidity below 60 %. EPR spectrometry was performed 14, 28 days, 3 and 6 months after irradiation. The dose dependence of the EPR signal and its attenuation over time were studied. An increase in EPR signal intensity with increasing dose was observed. The difference in signal amplitude between samples irradiated at 100 and 120 keV, depending on the dose, reached 8…55 % at day 14 and 12…62 % at day 28 (p ≤ 0,05). In the first 14–28 days, the signal decreased by 16…38 % (100 keV) and 16…32 % (120 keV), depending on the dose. After 3 months, the intensity decreased by 5…25 % (100 keV) and 5…47 % (120 keV), relative to the data of day 28. After 6 months, the signal intensity decreased by 26…33 % (100 keV) and 26…41 % (120 keV) relative to the 3-month data. The g-factor (at the zero-crossing point of the first derivative of the EPR signal) was 2.0048, confirming the presence of carbon-centred radicals.