Studies On The Changes Of Physiological Characteristics And Cell Cycle Of Primed Pinus Massoniana Seeds During Initial Germinating Stages

Seeds of Pinus massoniana. treated with PEG8000 solutions in different concentrations and treating time were cultivated at (15±1)℃. The best regime of PEG8000 treatment was chosen by measuring the changes of cell cycle, germination rate and vigor .The seeds treated with a suitable regime of PEG8000 for seed metabolism analysis during initial germinating stage were cultivated at (25±1)℃, the metabolic mechanism of PEG treated seeds during initial germinating stages was analysed by measuring the changes of stored nutrients and enzymes activities. The results were shown as follows:1.PEG8000 solution in suitable concentration and treating time could promote division of embryo cells and seed germination. The effects of priming enhanced along with the increasing PEG concentration and treating time. The best regime of PEG8000 treatment was 20%PEG+4days.2. The changing trend of respiratory rate was similar in both treated and untreated Pinus massoniana. seeds.3. The stored nutrients in Pinus massoniana. seeds were degraded, transfered and absorbed along with the prolonging of culture in both PEG8000 treated and untreated seeds. The stored nutrients in PEG8000 treated seeds were obviously lower than that in untreated seeds during the initial stage of seed germination, indicating that the seeds treated with PEG8000 solution entered the germination preparatory stage early compared with untreated seeds.4. Changing trends of activities of different enzymes in endosperms were similar in both PEG8000 treated and untreated Pinus massoniana. seeds. The activities of various enzymes in endosperms were significantly higher in PEG8000 treated seeds than in the untreated seeds. Activities ofα-amylase, proteinase and ACP increased during initial germinating stages and the peak value appeared at radicle emergence. Activities ofβ-amylase continuously increased and reached the peak value in the mid-and late period and slowly decreased there after.5. Changes of enzyme activities in various oxidative pathway were different in both treated and untreated of Pinus massoniana seeds. Activities of PGI in untreated seeds increased first and then declined along with prolonging of treatment, while the activities of PGI in PEG8000 treated seeds declined first than increased. Change of activities of G-6-PDH and 6-PGDH co-enzyme were similar in both treated and untreated Pinus massoniana seeds. The activities of G-6-PDH and 6-PGDH co-enzyme in endosperms was higher in PEG8000 treated seeds than in the untreated seeds.