International Journal of Horticulture, 2025, Vol.15, No.4, 162-170 http://hortherbpublisher.com/index.php/ijh 165 easier for flower buds to form. Ethylene might also work with other hormones to make sure flowering starts at the right time (Campos-Rivero et al., 2017). Abscisic acid (ABA) is usually associated with stress or dormancy in plants. In pitaya, abscisic acid also plays a significant role in flowering regulation, serving as a "balancing factor" for ethylene and helping to control the growth time and development mode of flowers. The combined effect of ethylene and abscisic acid constitutes a complex regulatory mechanism, emphasizing that hormonal balance is very important for the optimal flowering conditions of pitaya (Campos-Rivero et al., 2017; Holanda et al., 2021). 4.3 Hormonal interaction models During the flowering process of pitaya, it is a complex network integrating multiple hormone signals, and hormones do not act alone. Gibberellin, ethylene and abscisic acid all interact with each other and also interact with other signaling systems in plants. For instance, when the content of gibberellin decreased and ethylene and ABA were in equilibrium with each other, this indicated that the hormonal effects during the regulatory process of pitaya were dynamic (Shah et al., 2025). In flowering regulation, other hormones such as Auxin, Cytokinin and Brassinosteroid also play a role. Several hormones interact to dominate the signaling system, enabling the pitaya to transition from the vegetative growth stage to the reproductive growth stage. Understanding how these hormones work together can help researchers figure out how the flowering mechanisms of pitaya and other similar plants are formed (Shah et al., 2025). 5 Floral Morphology and Functional Adaptation 5.1 Petal and style structures for pollination The petals and style of the pitaya have undergone fine evolution, which is helpful for pollination. The flowers of Hylocereus undatus and H. polyrhizus, the red-fleshed pitaya, are larger and open at night. This kind of night-blooming helps attract nocturnal moths and other insects that are active at night. The large and open flowers provide sufficient landing space for pollinators, increasing the probability of successful pollination (Muniz et al., 2019). The spatial configuration of the stamens and pistils of pitaya flowers plays an important role in the pollination strategy of pitaya. In H. Undatus and H.polyrhizus, the arrangement of stamens contributes to efficient pollen transfer. The design of the positions of the stamens and pistils enables insects to easily touch the stamens and spread pollen. For instance, when bees or moths shuttle through flowers, they can simultaneously come into contact with both the pollen and the stigma, thereby enhancing pollination efficiency and ultimately achieving an ideal fruit setting rate. 5.2 Arrangement of stamens and pistils The way stamens and pistils are arranged in pitaya flowers helps improve pollination. In Hylocereus undatus and H. polyrhizus, stamens are set up so that insects easily touch them when moving around the flower. This means insects like bees and moths can quickly pick up pollen and deposit it onto the stigma, making pollination more effective. This arrangement is particularly helpful for H. polyrhizus, which needs insects for successful fruit production (Figure 2) (Muniz et al., 2019). The structure of pitaya flowers also suits different types of pollinators, both day-active insects like bees (Apis mellifera) and night-active moths. This ability to attract various pollinators improves the chances of pollination, helping the plant produce more fruit. Thus, the placement of stamens and pistils is very important for pitaya flowers (Muniz et al., 2019).
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