Effects of artificial aging on physiological quality and cell ultrastructure of maize (Zea mays L.)

‘Qiule 368’ (flour maize) and ‘Zhengdan 958’ (flint maize) seeds were artificially aged at 46 °C and 95% relative humidity to investigate the changes in physiological quality of maize seeds during aging. The vigor of the seeds, their reactive oxygen species (ROS) content, cell membrane status, antioxidant enzyme system, and cellular ultrastructure were all investigated. The results showed that the germination energy, germination rate, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities decreased during artificial aging, whereas the content of malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide anion (O2·–), and carbonyl protein as well as relative electrical conductivity (REC) increased during artificial aging. SOD and CAT activities showed highly significant negative correlation with aging time (p < 0.01), MDA, H2O2, O2·– content and REC showed highly significant positive correlation with aging time (p < 0.01), whereas POD activity showed significant negative correlation with aging time (p < 0.05). After aging, the cell membrane ruptured, and negative changes in amyloplast and protein bodies and in liposomes were all observed. This study provided guidelines for the meaningful study of changes in maize seed physiological quality during storage.