Optimizing nitrogen management based on nitrogen accumulation at key growth stages enhances quality and nitrogen use efficiency of soilless cultivated cut chrysanthemum

• Shifts nitrogen management from fixed-rate to a dynamic, plant-demand-driven strategy. • Quantifies the optimal nitrogen accumulation at five key growth stages for cut chrysanthemum. • Identifies stage-specific luxury nitrogen uptake, which reduces nitrogen use efficiency. • Determines precise daily nitrogen application rates for drip fertigation to achieve high quality. • Achieves a high apparent nitrogen recovery rate of 60–70% with optimized fertigation Cut chrysanthemum is a globally important high-value cut flower crop. Excessive nitrogen (N) application is prevalent in its production, leading not only to reduced flower quality and resource waste but also to environmental risks. However, the insufficient understanding of the dynamic N accumulation patterns throughout the entire growth cycle of chrysanthemum constrains the effective implementation of precision fertilization and scientific N reduction strategies. In this study, a two-year soilless cultivation experiment with a gradient of N application rates was conducted using the cut chrysanthemum cultivar ‘Nannong Xiaojinxing’. The study used principal component analysis (PCA) and regression modeling to systematically quantify the N requirements at key growth stages and to establish a precision fertilization strategy based on plant N accumulation. Results indicated that growth and quality indicators of chrysanthemum initially increased and then decreased with increasing N application, but the peak intervals varied among different indicators. Growth indicators were integrated via PCA into two principal components—phenotype and biomass—to generate a comprehensive score. Both this score and the cut-flower quality indicators were well-described by a quadratic regression model with N accumulation, thereby precisely determining the optimal N accumulation at each growth stage. Continued fertilization beyond the optimal N requirement induced luxury N absorption, consequently reducing N use efficiency. A conversion model between N accumulation and application rate was established. By applying the identified optimal N accumulation values to this model, the optimal N application rates were determined for the slow growth, rapid growth, flower bud differentiation, flower bud swelling, and flower color appearance stages as 89, 155, 35, 47, and 12 mg·plant⁻¹, respectively. Implementation of this optimized protocol resulted in a N agronomic efficiency of 140–160 g·g⁻¹ and an apparent N recovery rate of 60%–70%. This study pivots the N fertilization strategy for cut chrysanthemum from a fixed-amount regime to a dynamic management system centered on the plant’s optimal N status, thereby providing a robust pathway to on-demand fertilization, scientific N reduction, and stable quality production.