Abstract: 【Objective】 The objective of this experiment is to study the changes of endogenous hormones in grape shoots during the flower bud differentiation process and analyze its functions on grape flower bud formation and to provide a theoretical basis for solving the problem of “alternate bearing” in grape facilities and promoting early cultivation. 【Method】 Four-year-old beta grafted ‘Jingmi’ (V. vinifera CV. Jingmi, a weak light resistant variety, sustainable productivity can be obtained under early maturing cultivation in sunlight greenhouse without taking any measures) and ‘Summer Black’ (V.vinifera-V. labrusca CV. Summer Black, a weak light unresistant variety, sustainable productivity can be obtained under early-maturing cultivation in sunlight greenhouse needs renewal pruning) were used as materials, the experimental treatments of early maturing promoting cultivation in greenhouse (‘Jingmi’and ‘Summer Black’) and the opening field cultivation (‘Summer Black’) were designed, the process of flower bud differentiation in sampling period and the differentiation ratio were mapped and the flower bud differentiation process was observed by means of paraffin sectioning, through collecting the grape shoots which its roughness of the first node was greater than 0.5 cm and choosing the main winter bud of 2-3 nodes as the research material. At the same time, the contents of GAs, ZRs, ABA and IAA and the ratio of endogenous hormone levels of shoots base 2-3 nodes period were determined by using enzyme-linked immunoassay. 【Result】 The changes of endogenous hormones content in shoot were observed as follows: They were different from ‘Summer black’ with the poorest flowering in greenhouse, endogenous ZRs contents in shoots of ‘Jingmi’ with good flowering in greenhouse and ‘Summer black’ in open field showed a steadily rising trend since undifferentiation stage of embryo shoot growing point (5-7 leaves separated) to Bipartite stage of embryo shoot growing point (early flowering period). Since dome or flat differentiation stage of embryo shoot growing point (inflorescence separated) to anlagen differentiation stages (fruit-setting), endogenous ABA content increased rapidly. Since undifferentiation stage of embryo shoot growing point (5-7 leaves separated) to anlagen differentiation stages (berry enlarging begin), endogenous GAs content showed a trend of down-upward-down. Endogenous IAA content was higher in the whole flower bud differentiation process. The changes of endogenous hormones ratio in shoot were as follows: They were different from ‘Summer black’ with poorest flowering in greenhouse, endogenous ZRs/GAs ratio in shoots of ‘Jingmi’ with good flowering in greenhouse and ‘Summer black’ in open field increased significantly from inflorescence separating stage (from dome or flat stage of embryo shoot growing point to bipartite stage) and berry enlarging stage (from anlagen appearance to formation of the main axis of the inflorescence primordium and second branching of inflorescence primordium). The ratio of endogenous ZRs/IAA rose slightly since inflorescence separating stage (from dome or flat stage of embryo shoot growing point to bipartite stage), then held steady at lower levels from dome or flat stage of growing point to second branching differentiation stage of inflorescence primordium. Endogenous ABA/GAs ratio in shoots increased significantly at the late fruit enlarging stage (from anlagen appearance to formation of second branching of inflorescence primordium). Endogenous ABA/IAA ratio in shoots maintained at a lower level after fruit enlarging stage (from anlagen appearance to differentiation stage of the main axis of the inflorescence primordium). 【Conclusion】 The time before berry enlarging stage was the key moment of differentiation and regulation of flower bud. Endogenous GAs content in shoots showed less changes before berry enlarging stage, ZRs content before flowering beginning and ABA content from inflorescence separating to fruit setting rapidly declined, endogenous IAA content in shoots was low in the flower bud differentiation process. They could be the main reasons why grape in greenhouse could not form good quality flower buds. Endogenous hormones regulate the grape flower formation by balancing and cross-interacting at the specific period. Endogenous ZRs/IAA ratio in shoots maintained lower and stable after inflorescence separating stage was in favor of the formation of flower bud. The ratio of endogenous ZRs/GAs increased significantly at inflorescence separating stage and berry enlarging stage. The higher ABA/GAs ratio and the lower and stable ratio of ABA/IAA promoted the formation of anlagen and the main axis and second branching of inflorescence primordium after berry enlarging stage.

Key words: grape, flower bud differentiation, shoot, endogenous hormones, protected cultivation to promote early maturing