In vitro propagation of palm oil is still an obstacle for mass propagation due to the low plant regeneration frequency. The objective of this study was to investigate the effect of N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) on a somatic embryo (SE) proliferation and plant regeneration of oil palm SUP-PSU1. At an approximate size of 5 mm, SE from chopping with a sharp razor blade at 100 times was cultured on oil palm culture medium (OPCM) with 0.1 mg/L dicamba and different concentrations CPPU. The results showed that 0.3 mg/L CPPU gave the highest SE proliferation at 100 % and the number of SEs at 5.16 embryos/tube after 4 weeks of culture. SE was transferred to Murashige and Skoog (MS) medium supplemented with 0.2M sorbitol, a secondary somatic embryo (SSE), which was induced at 66.67 % with 21.2 embryos/tube after 8 weeks. Furthermore, cultured SSE on PGR-free MS medium for 8 weeks gave the highest germination rate at 65 %, with the number of shoots at 2.29 shoots. Thus, this study provides new information for improving the plantlet regeneration system through somatic embryogenesis in oil palm.

Mangrove fan palm is an endemic plant that grows well and has for a long period been related to traditional ceremonies in southern Thailand. It is an endangered plant with a slow growth and is difficult to propagate in mass production. Tissue culture technique can be used to produce a large number of plants within a short time and to preserve in vitro germplasm resulting in the plant not becoming extinct from natural habitats. Thus, the objectives of this research were to study effects of auxins and embryo preparation on somatic embryogenesis. The sterile immature zygotic embryo was cultured on MS medium with different types and concentrations of auxins. The results showed that 1 mg/l dicamba gave the best results in callus induction at 100% and callus diameter at 4.67 mm after 8 weeks of culture. For callus proliferation, callus chopped at 100 times and transferred to 0.1 mg/l dicamba containing oil palm culture medium gave the highest callus diameter at 10.33 mm after 4 weeks of culture and somatic embryos were also produced. Upon transferring somatic embryos to MS medium with 0.2 M sorbitol, a large number of various developmental stages of secondary somatic embryos were induced within 4 weeks. Therefore, the finding of this study could be highlighted that dicamba and chopping callus have an important role to induce callus and somatic embryo. This is the first report achieved on in vitro propagation of this plant and it will be beneficial for genetic conservation and biotechnological applications in the future.

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