Embryo Development of Dendrobium officinale in Relation to Seed Germination In Vitro

In this study, we focus on the zygote and embryo development process and the seed germination system in vitro of Dendrobium officinale. Two-celled embryo to early globular embryo could be found in seeds collected at 60 days after pollination (DAP). Seeds at 120 DAP were considered to be at the optimal maturity for asymbiotic germination when their embryos reached the late globular stage. Based on the results on embryo development and optimal seed maturity, culture media and organic supplements were tested to improve the seed germination percentage. Modified B5 medium showed the highest germination percentage, followed by culturing in MS and 1/2 MS media. The organic supplements included 200 mL L–1 potato juice or 100 mL L–1 coconut juice effectively increased the germination rate and improved the quality of the protocorms. The relationship between the defined process of embryo development and the seed germination in vitro showed that the seeds at 120 DAP in darkness culture condition in the modified B5 medium supplemented with 200 mL L–1 potato juice was the optimal combination to maximize germination. This study provides knowledge for large-scale industrial seedling production and for the further study of extraction medicinal ingredients from the protocorm of D. officinale.