Here we report the establishment of a transient hairpin RNAi-induced silencing system for colour modification assay in floral tissues of Dendrobium Sonia ‘Earsakul’, a tropical hybrid orchid with purple and white bi-coloured flowers. Portions of the D. Sonia ‘Earsakul’ anthocyanin-related genes chalcone synthase (DseCHS-B) and dihydroflavonol 4-reductase (DseDFR) which are required for anthocyanin synthesis,