Dynamics of petal pigments and morpho-physiological traits during flower development in Rosa 'Creamy Eternity'

As an important ornamental plant, rose (Rosa spp.) undergoes dynamic changes during flowering development, involving multiple indicators such as pigment composition, morphological structure, nutrient content, antioxidant capacity, and mineral element levels. However, the dynamic patterns and interactions among these physiological and biochemical indicators throughout flowering remain inadequately characterized. In this study, Rosa 'Creamy Eternity' was used as plant material, and five distinct developmental stages were examined: flower bud stage (S1), bud emergence stage (S2), bud swelling stage (S3), first bloom stage (S4), and full bloom stage (S5). Comprehensive analyses were conducted to assess dynamic changes in color parameters, pigment content, morphological structure, nutrient content, antioxidant capacity, and mineral element composition. The results revealed that: (1) During flower development, chlorophyll (Chl) content decreased markedly, while carotenoid (Car) and anthocyanin (AC) contents also declined. In contrast, flavonoid (Fla) content increased at stage S3, contributing to color stability. Petal color shifted from yellow-green to light yellow, accompanied by an increase in a* and L* values and a decrease in b* value; (2) cellular expansion and tissue development progressively refined petal morphology, increasing internal air space volume and petal thickness (PT). The upper epidermal cells transitioned from conical to flattened shapes, thereby enhancing light reflectance and overall brightness; (3) non-structural carbohydrates (NSC) accumulated during early flowering, after which starch (St) was broken down into soluble sugar (SS) to sustain energy metabolism. Soluble protein (SP) content increased continuously, reaching its peak at full bloom; (4) malondialdehyde (MDA) accumulation during early flowering likely activated the antioxidant enzyme system, which acted synergistically to alleviate oxidative damage by reducing MDA levels; (5) mineral elements exhibited significant correlations and functioned synergistically in regulating nutrient partitioning across flowering stages, with distinct elemental requirements at different phases; (6) stage S4 was identified as a critical period for floral organ development. In summary, optimized fertilization management during early flowering is recommended to enhance ornamental performance at full bloom. These findings provide a theoretical foundation for improved cultivation and flowering regulation in Rosa 'Creamy Eternity'.