Effect of the activation of germination processes on the sensitivity of seeds towards physical sanitation treatments

Physical treatments of seeds to eradicate pathogens have the risk of reducing vitality of the seeds. Seed lots may differ in sensitivity to these treatments, therefore factors influencing this sensitivity, including the physiological condition of the seeds, should be identified. In this study priming was used to mimic the effect of pre-harvest onset of germination on the sensitivity to these treatments. The effect of humidification, by incubation for one day at 100% RH, followed by drying back, on the sensitivity was also analysed. Primed, humidified and control seeds were subjected to hot water, aerated steam or electron beam treatments at various levels. Two seed lots from Daucus carota (carrot), two seed lots from Brassica oleracea (kohlrabi) and one seed lot from Allium cepa (onion) were used in the tests. Primed seeds from all seed lots were more sensitive to the aerated steam treatment and the B. oleracea and A. cepa seed lots were also more sensitive to the hot water treatment after priming. Priming had no effect on the sensitivity towards the electron beam treatment. Humidification had no effect on the sensitivity towards the physical seed treatments, with the exception of the humidified onion seeds, which were clearly more tolerant towards the aerated steam treatment. It is concluded that seed companies should be aware that the onset seed germination processes prior to harvest may increase the sensitivity of the seeds towards aerated steam and hot water treatments.