Colchicine- and Oryzalin-induced Tetraploids in Ornamental Alocasia X amazonica hort.

A procedure for chromosome duplication of Alocasia Xamazonica (2n=28) was established by using colchicine and oryzalin treatments to shoot tips of in vitro grown plants. Regenerated plants were screened by flow cytometry and their chromosome number was verified by cytological analysis of root tips. In total, 53 of 654 plants regenerated after the treatments appeared to be tetraploids and 144 plants were mixoploids. The treatments with colchicine and oryzalin produced 9.0 and 7.3 % and tetraploids, respectively. A maximum of 20 % tetraploid was obtained by the treatment with 0.05 % colchicine for 72 hr. Leaves of tetraploids have the tendency to be rounder, broader and thicker.