<![CDATA[Phalaenopsis gigantea is an endemic orchid species with high ornamental value but limited propagation efficiency using conventional methods. Somatic embryogenesis offers a promising approach for large-scale propagation; however, successful SE induction depends on appropriate plant growth regulator concentrations. This study aimed to evaluate the effect of different concentrations of 2,4-D on somatic embryogenesis induction in P. gigantea using the thin cell layer technique. The experiment was arranged in a completely randomized design with six concentrations of 2,4-D (0, 1, 2, 3, 4, and 5 mg L⁻¹), each replicated five times. Leaf-derived TCL explants were cultured on half-strength Murashige and Skoog (½ MS) medium and maintained for eight weeks. The observed parameters included percentage of somatic embryogenesis and embryogenic developmental stage. The results showed that somatic embryogenesis was induced only in explants cultured on medium supplemented with 5 mg L⁻¹ 2,4-D, with a somatic embryogenesis frequency of 60%. Lower concentrations of 2,4-D failed to induce embryogenic structures. Somatic embryos first appeared after eight weeks of culture and were morphologically identified as the globular stage, with no further development observed during the culture period. These findings demonstrate that 5 mg L⁻¹ 2,4-D was the only concentration within the tested range that induced somatic embryogenic structures in P. gigantea through the TCL technique.]]>
