Effect Of Seed Priming On Germination And Physiological And Biochemical Changes Of Alfalfa (Medicago Sativa L.) Under Salt Stress

Three alfalfa (Medicago sativa L.) variety seeds, cv. Victoria , Golden Empress and Victor, were used to investigate the effects of different priming methods on improving germination and growth under high-level salt stress (0.8% NaCl) conditions. The results are as follows:After alfalfa seeds were subjected to priming with H2O (hydropriming), 20% PEG6000, 2% KNO3 and 2% KNO3-KH2PO4 solutions respectively, germination percentage, energy of germination, germination index, root length and shoot dry weight, root vigor and activity of several enzymes were measured under the high-level saline conditions. The results showed that germination index of alfalfa seeds in Victoria and Golden Empress primed by four priming solutions was significantly higher than those of the non-primed seeds. All priming solutions improved the seed germination and seedling growth under the salt stress condition. Among the four priming solutions, 2% KNO3-KH2PO4 solution priming had the best effects on alfalfa seeds, that significantly increased germination (%), energy of germination, germination index, the dry weight of seedling, root length and enhanced activities of catalase (CAT), a-amylase and root dehydrogenase.When four priming solutions in combination with fungicide (5% carbendazim), the priming effects were similar to the effects primed by four priming solutions. However, fungi on seeds were less observed.After alfalfa seeds were primed with 2.4ppm BR, the results showed that germination percentage, germination index and vigor index of alfalfa seeds were .significantly higher than those of the non-primed seeds under the high-level saline conditions in three varieties. The priming significantly increased the root length and activity of root dehydrogenase. During seedling growth, the pnmed seeds significantly reduced the MDA accumulation. The activity of POD, CAT and SOD was significantly increased in Victoria and Victor seedlings. The suitable BR concentration in the priming was 2.4 ppm.Germination percentage, germination index, vigor index and energy of germination of three varity seeds were significantly increased as compared with the non-primed seeds after primed by sand. The sand priming also improved the dry weight of seedling and enhanced the activity of CAT and SOD of three alfalfa varieties. During seedling growth, the primed seeds also significantly reduced the MDA accumulation compared non-primed seeds. It was discovered that sand priming significantly increased the soluble sugar content, however, did not significantly increase the proline content under saline conditions.Sand in combination with 2% KNO3-KH2PO4 priming also gave a good results, however the results were similar to the results by sand priming alone.The experiments showed that different priming methods could improve seed vigour under high-levelsalt stress. Priming method can be chosed according to real situation. The sand priming was easy to handle, it is possible to be used in crop production in the future.