Objective Aiming at the bottlenecks in seedling propagation of Cinnamomum loureirii Nees., this study established an efficient cutting propagation technical system for the species, to provide key technical support for the vegetative propagation and large-scale standardized production of high-quality seedlings of C. loureirii.

Method C. loureirii cuttings were used as experimental materials in this study. The effects of different cutting substrates, plant hormone types, indole-3-butyric acid (IBA) concentrations and soaking time on rooting rate and seedling growth of C. loureirii cuttings were systematically explored. Single-factor preliminary experiments were firstly carried out to clarify the influence rule of each single factor on the rooting survival and new shoot germination of C. loureirii cuttings. On this basis, a four-factor and three-level orthogonal experiment was designed, and range analysis was performed to comprehensively analyze the effects of various factors on multiple growth indicators of cutting seedlings.

Result Hardwood cuttings were more suitable for the cutting propagation of C. loureirii than softwood cuttings. Among tested cutting substrates, the equal-volume (1∶1) mixed substrate of peat soil and loam exhibited the best cutting performance, with a rooting rate of 75.00%, followed by pure peat soil (70.83%) and the 1∶1 mixed substrate of loam and river sand (70.00%). In terms of hormone treatments, IBA, NAA and ABT all showed significant rooting-promoting effects, with the rooting rate of 76.67%, 75.83% and 72.50% respectively. The IBA treatment with a concentration of 200 mg/L and soaking time within 30 min achieved the highest rooting rate of cuttings, while the 400 mg/L IBA concentration was conducive to the growth of new shoots and root systems of cuttings. The range analysis of orthogonal test results indicated that hormone soaking time and hormone concentration were the dominant factors affecting the rooting and growth of C. loureirii cuttings.

Conclusion For the cutting propagation of C. loureirii, hardwood branches are the optimal cutting materials. The equal-ratio mixed substrates of peat soil and loam or loam and river sand are suitable for cutting cultivation. Soaking cuttings in 200 mg/L or 400 mg/L IBA solution within 30 min can obtain a high rooting rate and excellent seedling growth performance. This technical system is simple and convenient to operate, which can effectively support the seedling breeding of C. loureirii and provide a practical basis for large-scale clonal seedling cultivation in suitable areas such as Guangdong Province.