DOES HUMIDIFICATION TECHNIQUE ACCOMPLISH PHYSIOLOGICAL ENHANCEMENT BETTER THAN PRIMING IN ONION SEEDS?

In this study, hydration (priming with PEG 8000 and humidification) treatments were carried out in seeds of onion cultivars ‘Akgün-12’, ‘Valencia’, ‘TEG-502’ and ‘Contes’ (having approximately 80% viability) in order to investigate their effects on germination rate, mean germination time (MGT), total lipid, total protein, soluble protein and malondialdehyde (MDA) contents and catalase activity.
Priming treatments increased germination rate in cultivars ‘Akgün-12’ and ‘Contes’, however, no significant effect was observed in cultivars ‘Valencia’ and ‘TEG-502’. Priming treatments shortened MGT in cultivars ‘Akgün-12’ and ‘Contes’, nevertheless, prolonged in cultivar ‘TEG-502’. Moreover, no significant change was observed in cultivar ‘Valencia’. Humidification treatments increased germination rate and shortened MGT in all the cultivars. While priming treatments had no significant effect on total lipid and protein rates in all the cultivars, humidification treatments reduced total lipid rate but increased total protein rate. Hydration treatments did not have any significant effect on soluble protein content in seeds of all the onion cultivars. Following hydration treatments, MDA content decreased in cultivars ‘TEG-502’ and ‘Contes’, however, there was no significant effect in cultivars ‘Akgün-12’ and ‘Valencia’. Furthermore, hydration treatments increased catalase activity in all the cultivars. On the other hand, humidification treatments increased catalase activity more than priming treatments.
Consequently, instead of priming, humidification technique is recommended for onion seeds as a general practice in gene banks and seed companies, since it is a more economical treatment in terms of time and expenses and its ease of use.