Study On Changes Of Inclusions And Metabolism During Dormant Period Of Qiyuesu Pear

Pyrus sorotina is a perennial herb belonging to Pyrus Linn., and Rosaceae. Pear is one of the most extensively cultivated temperate fruit crops and is polular by people around the world. To adapte to environmental and climatical changes in winter, northern deciduous fruit trees evolved into biomechanism of dormancy after long period. The physiological and biochemical metabolisms did not end, but even were inactivited. Using Qiyuesu as materials in this experiment, systemically effects of temperature daily cycle and treatment on the accumulation of chilling requirment were studied. The dissertation systematically studied the mechanisms of Qiyuesu dormancy. The effect of SA and GA₃ treatments on the release of endodormancy of nectarine branches were analyzed and compared and the mechanism of pear dormancy is dicussed. Pathways of cell signalling and their ralationships during the pear dormancy were also explored by using growth regulator experimanets. The main results are as following:1. It is indicated that results from 0⁷.2℃chilling unit was the same as Utah models in measuring the chilling requirement. But result from 7.2℃chilling unit is too high, so this unit is not able to be used to measure deciduous fruit chilling reqirement.2. Dynamic regulation of content in dormancy pear branches: the content of H₂O₂ was rising continually in early stage of dormancy and was dropping quickly in consequent stage. The time during which the H₂O₂ content dropped sharply was consistent with the time of endodormancy release. Along the hole period of dormancy SA treatment and GA₃ treatment raised the H₂O₂ content. H₂O₂ was not the simple chain type relations in the paretree dormancy mechanism, but might be a kind of more complex mutual mechanism.3. SOD activity was keeping low,and then experienced a small peak; POD activity was rising during the whole dormancy period. As chilling requirement increasing, O2-.content rose constantly. Of the whole period of dormancy SA treatment and GA₃ treatment raised the SOD activity. The results show that the metabolism of reactive oxygen species has certain strong correlation with the natural dormancy of pear flower buds.4. The carbohydrate content experienced jump-change,starch and soluble sugar had the contradict changing trends during the whole dormancy period. The jump-change stage of the former two index were consistent with the dormancy. Along with the dormancy release,starch contents,(α+β)-amylase activity andα-amylase activity decreased. They may be one of the key enzymes for bulb dormancy controlling. 5. During dormancy release the protein content fell down sharply but the free amino acid content rose sharply .The jump-change stage of the former two index were consistent with the dormancy. In the late dormant period the protein content,DNA content and RNA content increased significantly .6. The effects of SA and GA₃ on the respiration metabolism of buds of pear in dormant period were studied. The results showed that in early dormant period the respiratory intensities of pear buds were relatively infirm and reduced slowly. At the lower temperature the respiratory intensities rapidly declined and after that they changed a little. In the late dormant period the respiratory intensities gradually rose. Under the nature condition three respiratory pathways showed different changes. PPP rose obviously. This showed that PPP might be the main reason of dormant relieve, this was in accordant with the study of seed. The SA made the PPP continuously enhanced.7. The Put,Spd and Spm contents in shoots of Qiyuesu were identified by HPLC analysis during SA and GA₃ treatment for dormancy release. And the content of Put,Spd and Spm changed little during break of dormancy. After dormancy release the Put,Spd and Spm contents rose sharply and the content of Spm was the highest. Correlation analysis of hormones content and ratio shows that Put /Spd and Put /Spm play a central role in dormancy controlling.8. The type and content of phenolic compounds in shoots of Qiyuesu were identified by HPLC analysis during SA and GA₃ treatment for dormancy release. There were many phenolic compounds in shoots of Qiyuesu. Five of them were identified,which were p-hydroxy-benzoic acid, pyrocatechol, p-coumaric acid, ferulic acid and salicylic acid. It is presumed p-hydroxy-benzoic acid and ferulic acid were likely to be the main promoters leading to dormancy breaking,and pyrocatechol, p-coumaric acid and salicylic acid might be the main inhibitor of releasing of phenolic compounds in shoots of Qiyuesu. Breakage of dormancy might be relative to cooperating control of these two kinds of phenolic compounds,which needs more study.9. The GA₃,IAA and ABA contents in shoots of Qiyuesu were identified by HPLC analysis during SA and GA₃ treatment for dormancy release. And the content of GA₃ increased during break of dormancy,while ABA decreased gradually. Correlation analysis of hormones content and ratio showed that GA₃ and ABA play the central role in dormancy controlling. The GA₃ treatment and SA treatment both accelerated GA₃ and IAA contents increasing.10. SA transmits the dormancy signal for H₂O₂ through unifing SOD by SA (H₂O₂ elimination enzyme), and leads to releasing of H₂O₂ content. Noted SA participated in the advancement of pear dormancy, which was possibly playing a role in signal amplification in this process, transmitting to H₂O₂, then completing the entire advancement of regulating dormancy. The effects of GA₃ on the responses of amylases in Qiyuesu were further investigated. GA₃ had effects on the activities ofα-amylase orβ-amylase.