The effects of osmopriming ‘Wolska' onion seeds on the percentage of normal and abnormal seedlings as well as the mean germination time (MGT) were studied. The priming was carried out with polyethylene glycol (PEG 6000 and PEG 8000) at 1.0 MPa and 1.5 MPa solutions. The seeds were treated in a column bioreactor for 6, 24, 48, 72 and 96 hours at 15 and 20ºC. Compared to the control (untreated seeds), both PEG 6000 and PEG 8000 osmotics similarly increased the percentage of normal seedlings, reduced the percentage of abnormal seedlings and shortened MGT. Seed priming at -1.0 MPa promoted a higher percentage of normal seedlings and shorter MGT than treatment at -1.5 MPa, but both osmotic potentials enhanced those germination features relative to the untreated seeds. Compared to the control, both priming temperatures improved the tested germination traits, but treatment at 20ºC gave better results than at 15ºC. Seeds primed for 48 hours produced the highest percentage of normal seedlings and the lowest number of abnormal seedlings, but treatment for 72 hours reduced MGT the most. The best ratios of normal to abnormal seedlings were obtained after priming at 20ºC for 24 hours at -1.0 MPa and ...
