Study On Physiological Changes Of Different Jujube Varieties Requiring Cooling And Dormancy Lifting

Fruit tree dormancy is to resist the low temperature environment formed by a physiological phenomenon,fruit trees must reach a certain low temperature accumulation can be normal to relieve the dormancy,if not a certain low temperature accumulation will affect the normal growth and development of fruit trees,seriously will also affect the life of fruit trees.Therefore,to understand the difference in the amount of cooling required by different jujube varieties and the physiological changes during the period of dormancy release,the way of dormancy release of jujube trees was explored,and the selection and production cultivation of jujube facilities were explored.In this experiment,the dormant shoots of 40 jujube varieties in the jujube resource garden of Tarim University were used as the test materials for germination experiments,and three cooling demand estimation models were used to study the cooling demand combined with local temperature to determine the dormancy process of different jujube varieties under natural low temperature conditions,and to find out the cooling demand model suitable for Xinjiang Aral area and the varieties suitable for facility cultivation.The dormant shoots of the high-demand jujube variety‘Tailihong’,the medium-demand jujube variety‘Fucuimi’and the low-demand jujube variety‘Jingzao39’were used as test materials to determine the dynamic changes of nutrient content,active oxygen species and antioxidant system of jujube varieties in different dormant stages.The main findings are as follows:1.Combined with the climate temperature of the Aral region,it was found that most jujube varieties ended their dormancy in mid-to-early January.Among them,‘Gaga Jujube’,‘Sanbianse’and‘Mama Jujube’were released from dormancy at the end of December,which was the earliest variety to release hibernation;11 varieties such as‘Donglingwuhe jujube’and‘Shandong Pear Jujube’were released from dormancy in early January;10 varieties such as‘Junzao’and‘Rucuimi’were released from dormancy in early January,which was the intermediate variety to release dormancy;16 jujube varieties such as‘Dongzao’and‘Lajiaozao’were released from dormancy in mid-January,which is the latest variety to release dormancy.2.Among the three cooling demand models,the≤7.2℃model can show the difference between varieties well,which is more suitable for the estimation of jujube cooling demand in Aral area.The cooling demand of 40 jujube varieties was divided into three categories by using the≤7.2℃model:16 varieties with high cooling demand of the first category,with a cooling demand>of 1057 h.There are 15 varieties in the second category that require cold capacity,and the cooling capacity is between 889～1057 h;There were9 varieties with low cooling demand in the third category,and the cooling demand was<889 h.3.The soluble sugar content in the branches of three jujube varieties with different cold requirements of‘Jingzao39’,‘Fucuimi’and‘Tailihong’showed a downward trend after entering dormancy,and the starch content showed an increasing trend,and the change of soluble sugar and starch content when dormancy was lifted was opposite to entering the dormant stage.The change of soluble sugar and starch content can be used as one of the indicators to judge the dormancy process of jujube trees.With the advancement of jujube dormancy process,the content of protein and free amino acids showed a trade-off phenomenon,and the time when the protein content reached the peak and trough values corresponded to the time of entering and releasing hibernation,so the protein change was closely related to the dormancy process of jujube trees.4.In the process of dormancy lifting,the content of reactive oxygen O₂.^-and H₂O₂increased in the shoots of three jujube varieties with different amounts of cold required of‘Jingzao39’,‘Fucuimi’and‘Tailihong’,and the rapid decline date of H₂O₂content coincided with the date of dormancy release,so the increase in H₂O₂content was a characteristic change in the dormancy period of jujube trees,and the rapid decrease in H₂O₂content also represented the lifting of dormancy of jujube trees.5.During the lifting of jujube dormancy,‘Jingzao39’、‘Fucuimi’、‘Tailihong’SOD activity increased with the decrease of temperature,and SOD activity decreased when jujube trees were released from dormancy,POD activity showed an upward trend after dormancy was lifted,and the low cooling demand variety was significantly higher than that of medium and high cold demand varieties.6.During the release of jujube dormancy,the content of GSH and ASA in the shoots of three jujube varieties with different cold requirements of‘Jingzao39’‘Fucuimi’and‘Tailihong’increased with the release of dormancy,and the content of antioxidant substances increased with the production of active oxygen species,and the activity of GR and APX gradually increased after the dormancy was lifted,and the APX activity was always higher than that of GR.Therefore,the changes in ascorbic acid and glutathione content in the ASA-GSH circulatory system and the interaction of APX and GR enzymes can remove reactive oxygen species during the dormancy of jujube trees and resist low temperature stress.