Mitigation of stunted root abnormality in onion (Allium cepa L.) using seed priming treatments

A high proportion of onion seed lots produced in Tasmania, Australia have had an unacceptable percentage of abnormal seedlings in germination tests and have been commercially unacceptable or required grading before being saleable. This study investigated the effects of hydro and osmotic priming, hardening and gibberellic acid application on the incidence of the major abnormality, seedlings with stunted primary roots. All treatments were effective in reducing the incidence of abnormal seedlings compared with untreated seed. Hydro-priming halved the number of abnormal seedlings while reductions of 20% to 47% were obtained for the other treatments. Hydro-priming also resulted in significant improvement in other quality characteristics including germination percentage and rate and uniformity of germination. In addition to previously published uses, this study demonstrated that priming may have commercial application in salvaging onion seed lots with unacceptable percentages of abnormal seedlings.