High-concentration co-application of 2,3-Butanedione monoxime and gibberellic acid synergistically promote dormancy release and improve post-planting agronomic traits in lily bulbs

• A synergistic effect between BDM and GA₃ in promoting lily bulb dormancy release and improving post-planting agronomic traits. • Co-treatment (200 mg/L BDM + 100 mg/L GA₃) significantly accelerated dormancy release and improved emergence synchrony. • The combined application enhanced seedling growth uniformity, plant height, and flowering performance (85 % bud set). • Bulb scale compactness was preserved despite significant improvements in above-ground agronomic traits. • Provides a practical and effective chemical regimen for improving dormancy management in commercial lily production. Dormancy regulation is a major challenge for sustainable lily ( Lilium spp.) production, as incomplete or prolonged dormancy release impacts vegetative growth and flowering. Gibberellic acid (GA) is widely used to promote dormancy release, whereas 2,3-Butanedione monoxime (BDM), a plasmodesmata regulator, has recently been proposed as a potential dormancy-breaking agent. However, the combined effects of BDM and GA remain unexplored. Here, we evaluated the influence of single and combined BDM (50-200 mg/L) and GA₃ (100 mg/L) treatments on dormancy release, seedling establishment, and flowering performance in the cut-flower cultivar Lilium ‘Palazzo’. The results showed that high-dose treatments (200 mg/L BDM, 100 mg/L GA₃, and their combination) significantly accelerated dormancy release, as indicated by increased bud-to-bulb length ratios. High-dose co-treatment of GA and BDM further improved seedling emergence (>90 % by 48 days after planting), and enhanced plant height and growth uniformity relative to single treatments. At the reproductive stage, the BDM + GA combination enhanced floral bud set (85 % vs. 56 % in control), reduced blind flowering (15 % vs. 44 %), and increased flowering rate (85 %). Importantly, high-dose treatments did not compromise bulb scale compactness, although trade-offs with bulb weight were observed in highly flowering groups. These results demonstrate that BDM and GA act synergistically to improve dormancy release, seedling uniformity and flowering in lily bulbs. The proposed chemical regimen provides a practical strategy for enhancing lily production and offers new insights into the regulation of dormancy in geophytes.