| Jujube(Ziziphus jujuba Mill.), belonging to the genus of Ziziphus in Rhamnaceae, is a special fruit originated from China. It has a long history in utilizing jujube. As a species with many flowers, the flower bud differentiation of jujube is different from the other fruit trees. Its fruit set percentage only 1%~2% is low in general case. Flower formation of jujube closely related with pollination and fertilization is a complex physiological and biochemical and morphogenesis process, in which orphological characteristics and inherent metabolism varied with varieties. To understand and master the regular pattern of flower formation is of great significance to improve the fruit setting rate of jujube. In this study, we chose fresh jujube ‘Qiyuexian’ and dried jujube ‘Jiaxianchangzao’ to study their fruit-bearing shoots(FBS), formation process and endogenous hormones change rule which could provide theoretical basis and guidance for flower period management of jujube. The flower forming process was observed by standard light microscope, scanning electron microscope and stereoscope. The endogenous hormones content was determined by liquid chromatography-tandem mass spectrometry(LC-MS/MS). The main research results were as follwos.(1) The growth and development of FBS was ‘S’ type. ‘Qiyuexian’ and ‘Jiaxianchangzao’ jujube stock germination begun with 10 and 16 April, and fruiting branch sections germination started from 19 April and 23 April, respectively. Their FBS about 80 d growing periods almost had no difference.(2) Flowering dynamic of signle jujube stock had been studied. The results showed that it had significant differences among number of leaves, flower buds and flower of species. The flower number of ‘Jiaxianchangzao’ was twice as many as ‘Qiyuexian’. What’s more, the flower diameter, stalk, sepal longth and width of ‘Jiaxianchangzao’ were significantly higher than ‘Qiyuexian’, especially flower stalk closed to the fruit set. The flower disc rich in honey occupied the larger proportion, which was of great significance for pollination.(3) The jujube flower formation contained flower-bud differentiation and floral development. The single bud differentiation was divided into six stages: vegetative stage, initial stage, sepal differentiation, petal differentiation, stamen differentiation and carpel differentiation. Floral development went through seven stages: bud period, bud split, sepal spread, petal spread, stamen spread, filament wilting and ovary inflated. The bud differentiation of ‘Qiyuexian’ and ‘Jiaxianchangzao’ taking 11 d and 8d respectively owned different shape with each atages. The shape in flower bud stage had great difference, while it was barely noticeable difference in flower opening stages.(4) The content and variation tendency in flower formation process esisted individual differences between IAA, ABA and GA3, also among varieties. IAA content was always at low level in fruit-bearing shoots(FBS) of ‘Qiyuexian’ and ‘Jiaxianchangzao’, while it fell rapidly again after a sharp rise in flowers. ABA content had a significantly rise firstly and then decreased slowly in FBS, and it was similar to IAA in flowers. GA3 always remained at a low level, with the opposite tendency in FBS and flowers. It decreased slowly after a significant increase at 5 cm of FBS in ‘Qiyuexian’, while remained stable at a lower level after significantly decrease at flower bud split stage. GA3 in the process offlowering of ‘Jiaxianchangzao’ changed slightly, and was always in a stable state.Based on the results above, it is concluded that lower IAA, IAA/GA3 and higher ABA, GA3, ABA/GA3 and ABA/IAA were needed in flower bud incubation stage. In flower stage, it required high levels of IAA, ABA, ABA/GA3 and IAA/GA3, while relatively lower levels of GA3 and ABA/IAA. GA3 in the process of flowering of ‘Jiaxianchangzao’ changed slightly, and was always in a stable state. It proved that GA3 was not the main factor affecting flowering. |
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