Comparative Analyses of Resource Allocation and Anatomical Structures in the Distal and Proximal Regions of the Scape in Dendrobium Orchids with Long Flower Longevity across Different Growth Stages

The genus Dendrobium is highly valued in horticulture, particularly for its racemose inflorescences, Dendrobium used both as potted plants and cut flowers.The scape of these inflorescences is crucial for nutrient transport to the flowers and for their presentation.Despite its importance, the structural and physiological changes of the scape during the growth stages of Dendrobium flowers are not well understood.To address this, we studied Dendrobium 'Garnet Beauty', a variety with a racemose inflorescence.We conducted metabolomic profiling, physiological response characterization, and morphological observations during the mature and senescent phases of flowering, focusing on two distinct positions on the scape.Our results indicated that the distal and proximal flowers on the scape did not differ significantly in terms of the lifespan or morphological structure.However, the primary metabolite contents of the distal portion were significantly higher than those of the proximal portion and the total area of the vascular bundles and phloem in the distal portion was greater than that in the proximal portion, indicating high nutrient transport efficiency in the distal portion.The amino acid and derivative and organic acid contents of the scape increased with age, indicating efficient nutrient recycling and utilization within the flowers.These findings indicate that the scape may contribute to maintaining consistent flower longevity by enhancing the nutrient transport capacity and providing a storage function, thereby ensuring a steady supply of nutrients to flowers.These results provide theoretical support for Dendrobium fresh-cut flower breeding.