Photoperiod, light intensity, and vernalization regulate flowering in the novel fragrant Chrysanthemum 'Xiaokuixiang'

Accurate regulation of the flowering period is crucial for year-round production of Chrysanthemum. This study was conducted in an artificial climate chamber to systematically investigate the effects of light intensity, photoperiod, and vernalization on the growth and flowering of a new fragrant Chrysanthemum (Chrysanthemum morifolium 'Xiaokuixiang'). Results showed that 'Xiaokuixiang' is a facultative short-day plant requiring at least 12 hours of darkness for flower bud differentiation, with 16 hours of darkness further optimizing this process. High light intensity (300 μmol m^-² s^-¹) significantly accelerated both vegetative growth and flowering. Although vernalization did not directly alter the differentiation rate under short-day conditions, it effectively shortened the vegetative growth phase and increased the number of normal flower buds. Combined treatment analysis revealed that plants pre-treated with low temperature exhibited optimal flowering performance under 300 μmol m^-² s^-¹ light intensity and short-day conditions (8 hours of light/16 hours of darkness). Based on these findings, an optimized production strategy is proposed: using winter-cold-exposed basal shoots as cutting materials, providing sufficient light during the vegetative stage, and promptly initiating short-day induction to achieve precise control over the flowering period of 'Xiaokuixiang'.