Effects of Different Light-Emitting Diode (LED) Illumination on Growth and Flowering in Chrysanthemum

Chrysanthemums (Chrysanthemum morifolium Ramat or Dendranthema grandiflorum (Ramat) Kitam) are short-day plants, and their growth and flowering are regulated through photoperiod control. Artificial lighting is widely used to manage flowering time, with fluorescent lamps traditionally employed. This study explores the impact of replacing fluorescent lamps with energy-efficient light-emitting diodes (LEDs) of varying spectra on chrysanthemum growth and flowering. Two cultivars (Sweet Pink and Polaris) were subjected to five light sources: fluorescent (18 W), red LED (7 W), blue LED (7 W), white LED (7 W), and grow light LED (3 W). Key findings demonstrated that white LEDs significantly promoted stem elongation, achieving marketable height (97.5 cm) while delaying flowering, aligning with the phytochrome-mediated flowering inhibition mechanism. Conversely, blue LED light accelerated flowering due to its influence on cryptochrome-mediated pathways. Additionally, white LEDs matched the growth performance of fluorescent lamps in leaf area and biomass while offering enhanced energy efficiency. These results elucidate the physiological mechanisms of light spectrum effects on chrysanthemum growth and flowering, supporting the use of LEDs as a sustainable alternative for chrysanthemum production