Rooting Efficiency of Camellia kirinoi in Different Exogenous Hormone Doses

Abstract

Camellia kirinoi is a golden camellia whose flowers have been used for human healthcare. Seedling production through cutting propagation provides uniform plant material and enables large genetic gains from superior genotypes for increased production. In this study, the effects of different doses of the exogenous hormone indole-3-butyric acid (IBA) on the rooting efficiency of C. kirinoi were investigated. Five IBA doses were tested, comprising 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% by weight in powder form, together with a control without exogenous hormone. Sand was used as the rooting medium. The results showed that IBA dose significantly affected the rooting efficiency of C. kirinoi. After 4 months of growth, the highest rooting rate (94.4%) was recorded with 0.4% IBA, followed by 0.2% and 0.5% IBA (approximately 91%), whereas the lowest rooting rates were recorded with 0.1% IBA (83.3%), 0.3% IBA (82.9%), and the control (82.3%). IBA dose also affected mean root length (MRL). The longest MRL was recorded with 0.4% IBA, averaging 4.18 cm, whereas 0.1% IBA (0.16 cm) and the control (0.15 cm) produced the lowest MRL values. In contrast, IBA dose did not significantly affect the number of shoots per cutting. It was concluded that 0.4% IBA by weight in powder form should be used for the cutting propagation of C. kirinoi. In addition, the cutting bed should be maintained at >95% humidity by spraying and shaded to provide 45–55% sunlight. These findings provide a practical, low-cost propagation protocol that nursery operators can apply to support large-scale seedling production and conservation of this endemic golden camellia.