Induction of tetraploids in ornamental Alocasia through colchicine and oryzalin treatments

Tetraploids were induced successfully from in vitro plants of diploid Alocasia 'Green Velvet' (2n=28) by treating shoot tips with colchicine or oryzalin. Colchicine at a concentration of 0.01, 0.05, 0.1% and oryzalin at 0.005, 0.01, 0.05% (both were dissolved in 1% DMSO, dimethylsulfoxide) were tested for 24, 48 and 72 h. Ploidy levels could be easily determined by flow cytometry. In total, 396 plantlets were investigated. Controls with DMSO maintained the diploid status; 22 tetraploids and 22 chimeras were obtained from treatments with colchicine and oryzalin. The most efficient condition for inducing tetraploids seemed to be treatment with 0.01% oryzalin for 24 h. Variation in the morphological characteristic of leaf shape was found among the multiplied plants under the same growing condition. While the leaves of diploids had elongated-heart shape, the leaves of tetraploids and chimeras tended to be round.