Flower opening is a vital process for reproductive success and fruit set, while a detailed understanding of mechanisms controlling this phenomenon still not clear. Although an internal circadian clock is held to regulate flower opening rhythms in several species, these mechanisms are likely influenced by environmental factors, including those exacerbated by climate change. Therefore, we hypothesize that the mechanism controlling flower opening is regulated by endogenous hormonal levels change. To test this hypothesis, we studied the heterodichogamous species Ziziphus jujuba under different light-dark regimes, analysing endogenous hormone levels alongside exogenous hormone treatments and inhibitors during the flower opening period. Furthermore, transcriptome analyses were conducted to elucidate the underlying molecular mechanisms. Our findings reveal significant increases in ABA and IAA levels at or following the time of flower opening. Exogenous auxin application accelerated flower opening, while auxin inhibitors reduced the number of opened flowers. The research provide that hormonal interactions play a critical role in flower opening regulation, as evidenced by transcriptome analysis correlating hormone pathways with gene expression. These findings from the study will extend the current knowledge of how the regulation of the time of flower opening in heterodichogamy plants and highlights the importance of understanding plant reproductive adaptations in climate change.