Seed Asymbiotic Germination Morphological Traits and Seedling Development in Cymbidium faberi Rolfe (Orchidaceae)

Cymbidium faberi Rolfe is a Chinese flower famous due to its beautiful floral pattern and strong floral scent and is also a threatened terrestrial orchid. Moreover, the traditional propagation method through tillers and symbiotic seed germination with the correct fungus under nature conditions could not meet conservation and commercial needs. Here, an efficient procedure for asymbiotic seed germination and in vitro seedlings development of C. faberi was successfully established through evaluation of time of seed collecting, seed pretreatments, light conditions and composition of culture media, respectively. Seed pretreatment with 1% NaClO for 30 min, dark culture on 1/4 MS medium containing 0.5 mg·L⁻¹ 6-BA and 0.1 mg·L⁻¹ NAA for 30 days and subsequent long day condition (14 h light/10 h dark photoperiod) culture on this medium for 30 days could obviously enhance the seed germination rate of C. faberi. The highest germination rate (85.0 ± 0.79%) was achieved when seeds were collected at 120 d after cross-fertilization, and then germination percentages progressively decreased. Furthermore, histological analyses from protocorm formation to seedling growth were explored. This study not only offers a reliable and scalable system for mass propagation to meet commercial and conservation demands but also serves as a foundational reference for physiological and molecular studies in Cymbidium and related orchids.