Effects of ultrasound and ascorbic acid treatments on the germination and physiological characteristics of aged Haloxylon ammodendron seeds

Seeds may undergo irreversible aging during long-term storage, causing a decline in the seed quality and yield. Reasonable repair treatments can improve the vigor and quality of aged seeds. In this study, an orthogonal matrix test method was used to study the influence of ultrasound temperature, ultrasound time, ascorbic acid (AsA) concentration, and AsA soaking time, on seed germination and the physiological characteristics of artificially aged Haloxylon ammodendron seeds, to evaluate if there were repair effects on the seeds and to identify optimal treatment conditions. The results indicated that an ultrasound temperature treatment and AsA treatment had positive repair effects on the aged seeds. The treatments significantly promoted (P < 0.05) the percentage of seed germinated, the germination potential, germination index, and seedling length. Further, the soaking liquid conductivity was decreased, as were the malondialdehyde (MDA) content and the proline content; however, the soluble protein content, superoxide dismutase (SOD), peroxidase (POD), and the catalase (CAT) activity increased. Ultrasonic temperature is one of the most important factors that can influence seed germination and seed vigor, it was concluded that the optimal treatment conditions for aged Haloxylon ammodendron seeds were an ultrasound temperature of 25 ℃, an ultrasound exposure time of 20 min, an AsA concentration of 300 mg·L^–1, and an AsA soaking time of 24 h.