Optimization In Conditions Of Naked Stratification And Re-drying Storage For Fraxinus Manshurica Rupr.Seeds

Naked stratification can effectively break Fraxinus mandshurica seeds’dormancy, and dormancy-released seeds can be re-dried and stored under optimal conditions in order to keep planting seedlings at any time. But this naked stratification and re-drying and storage techniques are still have some aspects need further improve. In this study, we use the Fraxinus mandshurica seeds as Materials, (1) to study the effect of different combinations of warm stratification duration, cold stratification duration and GA3 application methods on breaking seed dormancy during the process of Naked stratification.And analyze the embryo development, the change of endogenous hormones in different treatment during the process, To optimize the way of naked Stratification and reveal its Physiological Mechanism. (2) Study the effects of re-drying and storage during different stage of seed stratification (after the warm stratification and before cold stratification, during the cold stratification) on the dormancy-released seeds germination, and analyze the physiological changes of each treatment, to optimize the methods of seed’re-drying and storage and clarify its internal physiological mechanismthe. This study aims to provide more convenient and efficient stratification and re-drying Storage Technology for the Fraxinus mandshurica seeds sowing and seedlings.The main findings are summarized as follows:(1) Use the optimization naked Stratification method can shorten the Fraxinus mandshurica seeds’stratification time from 24-18 weeks,6 weeks in advance.The specific optimization method:Warm stratification at 15℃ for 10 weeks, cold stratification at 5℃ for 8 weeks and before cold stratification use GA3 treat this seeds before the cold stratification, After Fraxinus mandshurica seeds treated by this method, its germination was 85%,germination index was 5.76 and average germination time was 8.4 days. GA3 treatment could promote seed embryo development,the combination of warm stratification at 15℃ for 12 weeks, cold stratification at 5℃ for 8 weeks and use GA3 treat this seeds before warm and cold stratification help to increase the length of the embryo,and the combination of warm stratification at 15℃ for 10 weeks, cold stratification at 5℃ for 8 weeks and use GA3 treat this seeds before cold stratification conducive to the accumulation of embryo weight.During the naked Stratification, Different warm or cold stratification time and different stage use GA3 treat have no significant effects on ABA, GA3, IAA contents and GA3/ABA, IAA/ABA change both in embryo and endosperm.(2) Re-drying and storage seed after the warm stratification is more favorable to keep the seed germination rate, germination index, and shorten the mean germination time than re-drying and storage seed after the cold stratification. Re-drying and storage 16 weeks after the warm stratification then cold stratification to break dormancy the Fraxinus mandshurica seeds’ Germination Rate was still maintained at 85%, Germination Index was 6.82,Average Germination Time was 7.85 days. But the dormancy-released seed after re-drying and storage 16 weeks the Germination was only 61%, Germination idex was 3.75, Average Germination Time was 12.29 days.In the storage time of 16 weeks, the germination ability of the two treatments was not changed obviously. Re-drying and storage seed after the warm stratification is more favorable for keeping the cell membrane integrity of the seed embryo and endosperm than re-drying and storage seed after the cold stratification.And the lipid peroxidation of the embryo and endosperm cells is lower than which re-dried and stored after the cold stratification. Two different methods for re-drying and storage Fraxinus mandshurica seeds had no significant effect on the antioxidant enzyme system both in Fraxinus mandshurica seeds’ embryo and endosperm.