Induction of in vitro polyploidy in ornamental flowers of orchid species (Phalaenopsis amabilis)

Phalaenopsis amabilis is one of the best and well-known orchid species that is easy to grow and has good compatibility. This study was done for induction of polyploidy in Phalaenopsis amabilis by in vitro conditions. The study was conducted as factorial based on a completely randomized design with three replicates and each replicate including three explants of auxiliary buds (approximately 3 mm ) containing two leaves using seven different concentrations of colchicine (0, 0.01, 0.05, 0.1, 0.15, 0.2 and 0.25 percent) in two time periods (24 and 48 hours). Explants were cultured on MS medium without hormones after treatment with colchicine. After 10 weeks sevral morphological traits that were under influence of polyploidy, including number and size of leaves, number and size of roots, length and width of stomata guard cells, number of chloroplast, and survival rate of seedlings were evaluated. Cytological observations of new developed leaves were evaluated by flow cytometry to assess the number of chromosomes in plants. The results showed that the highest percentage of polyploidy was obtained using 0.15 and 0.2 percent of colchicine concentrations. Correlation of some morphological traits with polyploidy levels showed that in addition to flow cytometry method, some important morphological traits such as stomata characteristics and its density can be used to recognize polyploidy in orchid plant. Polyploidy was resulted to enhancement in size and reduction in density of guard cells. Colchicine is usable to produce ornamental polyploid orchid.