Studies On The Methods And Mechanbism Of Improving Eggplant Seeds Vigor And Seedling Resistance To Chilling By Seed Priming

In order to discover the methods and mechanism for improving seed vigor and seedling chilling resistance by seed priming,the changes of seed vigor and physiological indices during accelerated aging, this dissertation studied the effects of various seed treatments on seed vigor and physiological indices,and the primed seed's germination characters and seedling resistance to chilling under chilling stress were studied in this paper. The main results were as follows:1. Effect of accelerated aging on the vigor and metabolism of eggplant seeds.The changes of seed vigor and biological indices in eggplant seeds during the aging period were investigated using accelerated aging technique. The results showed that with the seed aging,the germination potential,germination rate, germination index and vigor index significantly declined compared with untreated seeds. The activity of antioxidase including POD,SOD and CAT , and the contents of soluble sugar and soluble protein in aged seeds also significantly decreased,while the relative conductivity and MDA content markedly increased. Polyacrylamide gel electrophoresis showed that with the seed aging, some of the bands of gliadin and esteras waned or disappeared. Chromosome bridges, chromo-some breakage and chromosome fragments were detected in aged seeds, chromosome aberration rate increased with the decline of seed vigor. Correlation analysis indicated the eggplant seed vigor indices were correlated with SOD activity, POD activity, soluble sugar content, and soluble protein content, and significantly negatively correlated with MDA content in the seeds.2.Study on the methods and mechanism of improving eggplant seeds vigor.The optimal priming combinations were screened with L9(34) orthogonal experiment design to the priming methods including imbibition-drying , low temperature , polyethylene glycol (PEG), CaCl2, KH2PO4, gibberellin (GA),6-BA,ascorbic acid (AsA) and Chitosan(CTS). The changes of seed vigor and physiological indices were investigated in accelerated-aged eggplant seeds after priming with the optimal priming combinations. The results indicated that all the treatments were effective to improve accelerate-aged seeds vigor,and GA treatment was the best one. With the rise of aged eggplant seed vigor after the seed priming, the activity of POD, SOD,CAT and dehydrogenase increased,and the relative conductivity (REC) and the content of MDA in aged seed significantly increased. Correlation analysis indicated eggplant seeds vigor indices were significantly positively correlated with the activity of POD, CAT,soluble sugar content and soluble protein content, and significantly negatively correlated with the MDA content in the seeds.3. Effects of seed priming on seed vigor and seedling growth under chilling stressOn the basis of optimal combinations obtained from previous seed priming, the seeds germination property and physiological indices of seedling under chilling stress were studied. The results showed that under low temperature, all priming treatment with the optimal combination significantly enhanceded the seed germination indices. At three-to four true leaf stage and five-to-six true leaf stage, the healthy seedling index of the primed seedling was significantly higher than those unprimed. After chilling stress at four-to-five true leaf stage,activities of POD,SOD and CAT,and contents of proline, soluble sugar and soluble protein in the leaves of primed seedling were significantly higher than that unprimed,and the relative electrical conductivity and the MDA content were significantly lower in the priming seedling leaves compared with non-priming seedling leaves. It indicated that seed priming with the nine methods improved not only the seed germination and seedling growth, but also the seedling resistance to the chilling.4. Effect of polyamine priming on eggplant seed vigor and seedling chilling toleranceEffects of Spd and Spm treatments on eggplant seed vigor and seedling chilling tolerance were studied under chilling stress. Seeds of eggplant hybrid'Fengyan 2'were soaked with 0.25 mmol·L-1of Spd and Spm, respectively for 24 h in dark under 15℃, 20℃and 25℃,while the control was not treated with Spd and Spm. The seed vigor indices and seedling chilling tolerance indices between treatment and untreatment were investigated and compared. Results showed that Spd and Spm treatments significantly improved seed vigor and seeding growth, enhanced the activities of POD,CAT and SOD, increased soluble protein and proline contents, and decreased membrance permeability and MDA contents .The results suggested that Spd and Spm played a vital role in promoting eggplant seed vigor and seedling chilling tolerance.