Effects Of Osmotic Priming On Physiological And Biochemical Characterstics Of Flue-cured Tobacco Seeds Germination

The trial materials was tobacco seeds in this experiment. PEG, H₂O₂, ATP, KNO₃ and GA₃ were chosen as the osmotic regulating agents.In the experiment, The tobacco seeds were soaked by single-agent priming treatment and combination priming treatments.The seed vigor,the respiratory intensity and the dynamic change of a lot of physiological and biochemical characterstics of tobacco seeds were tested, such as amylase activities, soluble sugar, malondialdehyde (MDA),the effects of different priming treatments on improvement of seed vigor and tobacco seedlings'physiological and biochemical changes were discussed 1. Choosing 20% PEG as the osmotic regulating agents, osmotic primied the tobacco seeds at 20℃for 24h,48h and 72h,then re-dried the tobacco seeds.The seeds which unsoaked and soaked in the water were selected as control group.The results of the seed germination experiment show that the germination percentage, germination energy germination index and vigor index of the tobacco seeds which were primed by PEG were increased significantly.The relative electrical conductivity of seeds lixivium was reduced.The respiratory intensity of seeds was increased significantly, the soluble sugar content and the fatty acid content of seeds were increaed,the soluble protein content was reduced,the activities of dehydrogenase, amylase,peroxidase and catalase were increased clearly on germination process of Seeds.Osmotic priming the tobacco seeds could reduced the malondialdehyde content of seeds but the effect is limited.The seeds were soaked in the 20%PEG for 48h had the best effect. 2. Adding the different concentrations of H₂O₂ and ATP as assistant agent into 20% PEG.The tobacco seeds were osmotic primied with different time.By comparing the germinating ability of the seeds primied,found the best concentration and priming time of two combination osmotic regulating agents,used the optimal treat- ment to prime the tobacco seeds and tested the change of physiological and bioche -mical characteristics during seed germination.The results show that PEG with assistant agent could improve tobacco seeds vigor clearly.PEG with 5mg/LATP primed seeds for 24h and PEG with 1%H₂O₂ primed seeds for 24h had the best effect on improving the germination percentage,germination energy germination index and vigor index of the tobacco seeds.After priming, The relative electrical conductivity of seeds lixivium was reduced. The respiratory intensity of seeds,the soluble sugar content and the fatty acid content of seeds were increased significantly,the activities of different kinds of enzymes were increased too,the soluble protein content was reduced,the osmotic priming could decreased the MDA content of the seeds in the first four days of seeds germination.3. Using the potassium nitrate solution and the gibberellic acid solution to soak the tobacco seeds, found the optimal treatment of the two osmotic regulating agents. From the change of seeds physiological and biochemical characteristics, after priming by potassium nitrate solution and gibberellic acid solution,the germination percentage, germination energy germination index and vigor index of the tobacco seeds were improved. The respiratory intensity of seeds was increased,the soluble sugar content and the fatty acid content of seeds were higher than CK, the soluble protein content was reduced, the activities of dehydrogenase, amylase,peroxidase and catalase were increased on germination process of Seeds.The gibberellic acid solution treatment could reduce MDA content of seeds in the previous stage of seeds germination.The results show that the change of physiological and biochemical characterstics of tobacco seeds primed by different priming treatments were different.however,all the treatments could improve seed vigor,reduce the relative electrical conductivity of seeds lixivium,improve the respiration , the substance metabolism and the activities hydrolytic enzyms and defense enzymes of seeds,some treatments could decrease MDA content of seeds in the previous stage of seeds germination,but the others had no more obvious effect.