Effects of disinfection, substrates, and plant growth regulators on scale propagation in <i>Lilium</i> spp.

Scale propagation is the predominant commercial method for lily bulbs due to its high efficiency, genetic stability, and direct virus elimination from bulbs. The morphology of scales is closely related to the growth of bulblets, and optimizing each step in the propagation process can also improve reproduction efficiency and bulblet quality. This study developed a growth prediction model based on the correlation between scale and bulblet morphology through a systematic evaluation of 20 lily varieties, offering a quantitative benchmark for lily producers to organize production tasks in a rational manner and minimize resource wastage. Additionally, the effects of different disinfection treatments, substrate compositions, and plant growth regulators (PRG) on the scale propagation of five lily varieties were investigated. The results revealed that a 1 g/L mancozeb treatment improved the propagation coefficient. Regarding substrate composition, a 1:1:1 mixture of peat, perlite, and vermiculite significantly increased bulb circumference and weight compared to imported peat. For plant growth regulators, pretreatment with 0.5 g/L CPPU (N-[2-chloropyridin-4-yl]-N'-phenylurea) notably enhanced the propagation coefficient, as well as bulblets circumference and weight. These findings provide optimized protocols and parameters for efficient lily bulb propagation, offering both theoretical insights and practical guidance for large-scale production.