Physiological and Biochemical Changes Occur in Onion Seeds during Ageing

In this study, physiological and biochemical changes at different viability levels were investigated in onion seeds, which lose their viability in a short period of time. For this purpose 95, 80, 60, 40 and 20% viability levels were obtained by controlled deterioration treatments in seeds of onion cvs. Akgün-12, Valencia and TEG-502. Subsequently, mean germination time, electrical conductivity, total lipid, total protein, soluble protein, malondialdehyde (MDA) and catalase activity measurements were conducted at these viability levels. Regarding the seeds of cv. Contes, same measurements were conducted at 80, 60, 40 and 20% viability levels since the initial seed viability was 80%. Depending on seed ageing, as mean germination time, electrical conductivity and MDA content increased, total lipid, total protein, soluble protein contents and catalase activity decreased. Moreover, the increase in mean germination time, MDA content and electrical conductivity and also decrease in catalase activity were more evident when seed viability of each onion cultivar decreased 60% or below this level, which was determined as a threshold.