Effects Of Priming On Physiological And Biochemical Changes Of Aging Barley Seeds

Objective: The decrease of seed vigor affects seed germination and seedling growth,and may even cause plant death.These effects are not conducive to the long-term storage of germplasm resources.Seed priming technology can significantly improve seed vigor and repair the damage caused by aging and deterioration to promote the healthy growth of plants.In this experiment,barley seeds of different cultivars were treated with aging treatment to reduce seed vigor,and then low vigor seeds were treated with different priming methods to improve their vigor.By studying the changes of some physiological and biochemical indexes during the restoration of vigor of aged barley seeds,the suitable priming methods and conditions for improving low vigor barley seeds were explored and the aging mechanism of barley seeds was clarified.It can provide practical reference for the improvement of barley seed vigor in the field and provide theoretical guidance and basis for the safe storage of barley seeds in the germplasm resource bank.Methods: Under the condition of temperature 40℃ and relative humidity 80%,the seeds of two different cultivars of barley,Ganpi4 and 0416-1,were aged to reduce the vigor of the seeds.Then,these low vigor seeds were treated by different initiators,concentrations and times.Next,the water absorption,germination characteristics,seedling growth characteristics,seed vigor,superoxide dismutase,peroxidase,catalase and hexokinase of seeds were measured in turn.The activity of 6-phosphate glucose dehydrogenase was determined and the contents of soluble storage substances and ATP were determined.Results:(1)The germination characteristics and seedling growth characteristics of barley seeds decreased after aging treatment.The germination rate,germination energy,germination index and vigor index of seeds were significantly increased,and the root length,bud length,dry and fresh weight of whole plant were significantly increased after priming treatment.(2)With the increase of aging degree,the water absorption and water absorption rate of barley seeds decreased significantly,while the malondialdehyde content and relative conductivity increased rapidly.The priming increased the water absorption and water absorption rate of barley seeds,decreased the relative conductivity and malondialdehyde content,and made the seeds germinate quickly and the plant growth accelerated.Moreover,the priming effect varies with the time of imbibition.(3)The contents of soluble storage substances,superoxide dismutase,peroxidase and catalase activities decreased in different degrees after aging treatment.The contents of storage substances and the activities of superoxide dismutase peroxidase and catalase of aged barley seeds increased significantly during germination after different priming treatments.The results showed that the effect of aging barley seeds was significantly higher than that of the control.(4)With the increase of aging degree,the activity of hexokinase and 6-phosphate glucose dehydrogenase in barley seeds decreased significantly,and the ATP synthesis rate slowed down.With the increase of imbibition time,the activity of these two enzymes and the content of ATP increased obviously.The synthesis rate of ATP increased significantly and became stable for a certain period of time.Conclusions: After different priming treatments,aging seeds promoted seed germination and seedling growth,reduced electrical conductivity and MDA content in seeds,accelerated water absorption rate and increased soluble storage material content.The activities of some antioxidant enzymes and key enzymes in glycolysis were increased,and the ability of ATP synthesis was enhanced,which alleviated and repaired the aging damage of seeds.