Optimization of Key Techniques for In Vitro Rapid Propagation of New Edible and Ornamental Lily Cultivars

Lilium, a traditional plant with dual medicinal and ornamental values, is restricted in its industrial development by the low natural propagation rate of bulbs and dependence on imported high-quality germplasm. To address this bottleneck, this study used new lines of LA hybrid lilies and Asiatic hybrid lilies (three cultivars) as experimental materials to establish an efficient and stable tissue culture and rapid propagation system. Key procedures including disinfection of different explants (bulb scales and capsules), adventitious bud induction and proliferation, rooting culture, as well as acclimatization and transplantation were systematically evaluated. The results showed that bulb scales were superior to capsule seeds as explants in tissue culture (contamination rate 9.44%, regeneration rate 11.92%). After disinfection with 75% ethanol combined with 10% sodium hypochlorite, the contamination rate could be controlled at 14.29–21.43%, and the regeneration rate reached 100%. Supplementation with 50 g·L−1 sucrose + 1 mg·L−1 6-BA + 0.1 mg·L−1 NAA (Treatment TA1), 50 g·L−1 sucrose + 2 mg·L−1 6-BA + 0.5 mg·L−1 NAA (Treatment TA4) in MS medium, combined with dark culture, could effectively promote adventitious bud induction, proliferation and bulblet enlargement. For the rooting stage, the optimal media were 1/2 MS + 0.5 g·L−1 activated charcoal + 2 mg·L−1 6-BA + 0.5 mg·L−1 NAA (Treatment TB4) or MS + 0.3 g·L−1 activated charcoal + 2 mg·L−1 6-BA + 0.5 mg·L−1 NAA (Treatment TB1), and the highest rooting rate of ‘Pink Renault’ reached 100%. When plantlets from all three cultivars were combined and acclimatized and transplanted into sterilized peat soil, the overall survival rate was 89.33%. The TOPSIS method was also adopted for comprehensive evaluation to screen out the optimal culture conditions for different varieties. Based on phenotypic observation and physiological index data, ‘Pink Renault’ showed great potential as an excellent propagation germplasm. The integrated and optimized technical system provides a feasible solution for large-scale and industrialized seedling production of medicinal and ornamental lilies, and is of great practical significance for the efficient utilization of germplasm resources and sustainable development of the lily industry.