Proliferation of somatic embryo and plantlet regeneration of indigenous robusta coffee -

Abstract

Robusta coffee is an important commercial crop of Thailand. Currently, tissue culture techniques are used to propagate Robusta coffee through embryogenesis. However, somatic embryo induction of indigenous Robusta coffee is still limited. Thus, this study aimed to enhance the proliferation and germination of the somatic embryos. Initial inoculum of somatic embryos and types of auxin was studied by culturing somatic embryos at globular stage at 10, 20 and 30 embryos in liquid MS medium supplemented with 2 mg/L BA in combination with different types of auxin (IBA or 2,4-D) at a concentration of 0.50 mg/L for 6 weeks. The results showed that 30 embryos were cultured in IBA gave the highest number of somatic embryos at torpedo stage at 20.67 embryos. After that, somatic embryos at torpedo stage were transferred to solid or liquid MS medium supplemented with 2 mg/L BA without or with 0.50 mg/L GA₃. The results showed that liquid medium with 0.50 mg/L GA₃ gave the best result in plant regeneration in terms of survival rate at 100%, germination rate at 90%, plant height at 0.59 cm and number of cotyledon leaves at 1.95 leaves after culture for 4 weeks.