| Jujube（Ziziphus jujuba Mill）,belonging to the genus of Ziziphus in Rhamnaceae,it is native to China and has a long history of cultivation.The flower bud differentiation of jujube is different from other fruit trees.It belongs to differentiation in the same year and flowering in the same year.The differentiation period is short and the differentiation speed is fast.It can differentiate continuously and repeatedly in the whole flowering process.Flower bud differentiation is a more complex process than vegetative organ differentiation.It is a very important period in the growth and development of fruit trees.It is closely related to production and directly affects the quality and yield of fruit.In this study,the morphological changes of Huizao and Junzao during flower bud differentiation were observed,and the dynamic changes of antioxidant enzyme activities,nutrients and endogenous hormone contents during flower bud differentiation were determined.At the same time,different concentrations of exogenous gibberellin were sprayed at the full flowering stage to observe and determine the pollen vitality and stigma receptivity,so as to reveal the physiological and biochemical process of jujube flower bud differentiation and the regulation mechanism of flowering period.It is expected to artificially regulate the quality of jujube flower bud,and provide theoretical basis for breeding and high-yield cultivation.The main results are as follows.（1）The process of flower bud morphological differentiation of Huizao and Junzao can be divided into six stages.It takes 7 days and 11 days respectively from flower primordium differentiation to pistil differentiation.The life span of single flower of jujube is short.There are six periods from bud cracking to ovary enlargement in Huizao and Junzao,and there is no significant difference in each stage of flower development,but stigma cracking and pollination and fertilization of Junzao are earlier than those of Huizao.（2）In the process of flower bud differentiation,IAA,GA3,and ZT showed a downward trend before the sepal differentiation period,and then the GA3,ZT and IAA content in Huizao gradually increased.From sepal differentiation stage to petal differentiation stage,IAA content of Junzao increased significantly,then decreased and then increased.From primordium differentiation stage to sepal differentiation stage,ABA content of Huizao increased significantly,while Junzao decreased significantly.With the progress of differentiation,ABA content of Huizao decreased gradually after sepal differentiation stage,while Junzao increased gradually and reached the peak at pistil differentiation stage.The results showed that high IAA and ABA contents were not conducive to flower bud differentiation.（3）After the start of flower bud differentiation,the ABA/IAA,ZT/IAA,and GA3/IAA ratios of Junzao rose rapidly,but the GA3/ABA and ZT/ABA ratios showed a downward trend.The ZT/IAA and GA3/IAA ratios of Huizao increased significantly and then decreased during the period of flower primordium differentiation to sepal differentiation.After differentiation,the ratio of ZT/IAA and GA3/IAA was lower than that of flower primordium differentiation.These results indicated that higher ratios of ABA/IAA,ZT/IAA and GA3/IAA could promote flower bud formation.（4）The contents of soluble sugar and reducing sugar in flower bud of Huizao were relatively flat from flower primordium differentiation stage to petal differentiation stage.When the pistil differentiation stage is transferred,the soluble sugar content decreases,but the starch content continues to rise.The content of starch and soluble sugar in flower bud of Junzao decreased sharply from flower primordium differentiation stage to sepal differentiation stage,but the content of reducing sugar decreased little.The content of soluble sugar,starch and reducing sugar reached the highest value in petal differentiation stage and stamen differentiation stage.The content of soluble protein changes in contrast to the content of carbohydrates,from the period of flower primordium differentiation to pistil differentiation,which increases first and then decreases.Therefore,high content of reducing sugar,starch and soluble protein is conducive to the morphological differentiation of Jujube Flower bud.（5）The activity of SOD in flower bud of Huizao and Junzao first increased and then decreased from flower primordium differentiation stage to sepal differentiation stage,then the content of SOD in Huizao decreased continuously,while Junzao increased significantly.The POD,PPO,and CAT activities of the two varieties were basically the same in the whole differentiation process.After the flower buds began to differentiate,the POD,PPO,and CAT activities gradually decreased,and the lowest point appeared in the pistil differentiation period.From this result,the reduction of protective enzyme activity is conducive to the initiation of different differentiation stages of jujube flower buds,and it is conducive to flower bud differentiation.（6）Junzao reached the highest vigor and germination rate on the second day after treatment with concentrations of 10 mg/L and 20 mg/L,while Huizao reached the highest value on the third day with the same concentration.The pollen tube length of Junzao was the longest on the second day of treatment with a concentration of 10 mg/L,reaching 758.64μm.The pollen tube length of Huizao was treated with a concentration of 20 mg/L,reaching 672.09μm on the third day.The acceptability of stigma and the amount of pollen showed that low concentration（10 mg/L～30 mg/L）had a certain promotion,while high concentration（50 mg/L）had an inhibitory effect. |
