Electron seed dressing of barley—aspects of its verification

Seeds (e.g. cereal grains) are treated with low energy electrons for seed dressing to inactivate phytopathogenic organisms on their surface and in the seed coat. To verify the electron treatment of barley by e-ventus® technology, three physical detection methods were investigated: photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR). Influencing factors such as storage time and temperature, geographic origin of samples and light exposure were studied. All three detection methods proved to be suitable, with PSL being the most convenient. But also ESR by measuring the barley husks offered a simple and rapid verification. Although TL was more laborious to perform, it was highly reliable. PSL was able to classify electronically dressed seeds after storage times of at least 12–13 months independent of storage temperatures, assayed in the range of 5–23 °C. The applicability of ESR after storage was dependent on the measuring system used and on storage temperature. At room temperature the advanced E-Scan™ spectrometer allowed verification of treatment for at least 7.5 months, whereas the EMS 104 spectrometer was applicable only up to 2 months of storage. Storage temperatures of 5 °C markedly prolonged the verifiability of treatment. Using TL, treated samples stored at room temperature could be easily verified for at least 13 months. Fading of the PSL signal of treated barley was observed under the influence of light, the extent of fading being influenced by illuminance but not by treatment of the samples with high or low energy electrons. Contrary to PSL, TL and ESR were found to be still applicable for the detection of treated barley exposed to light.