IN VITRO AND IN VIVO POLYPLOIDIZATION OF DRACAENA WITH ORYZALIN

Polyploid forms of plants often have horticulturally desirable characteristics such as more compact growth habit, thicker and more robust leaves, and a deeper green color. Dracaenas are an important foliage plant not only in the United States, but also worldwide, and a polyploid form with new desirable characteristics would be helpful in maintaining consumer demand. In addition, a polyploid form could be useful for creating variety in hybridizing efforts. Two methods of polyploidization on Dracaena were attempted. The first method treated developing axillary buds of D. deremensis ‘Santa Rosa’ in vivo by placing oryzalin soaked cotton on the meristem and wrapping in plastic. The second method treated callus tissue of D. deremensis ‘Lisa’ in vitro by soaking the calli in oryzalin solution. Both methods employed six treatments consisting of 3 concentrations of oryzalin and 2 durations of treatment: 0% for 24 hours, 0% for 48 hours, 0.005% for 24 hours, 0.005% for 48 hours, 0.01% for 24 hours, and 0.01% for 48 hours. The developed shoots from the axillary buds and the regenerated shoots from the callus tissue were tested for conversion to polyploidy using flow cytometry with leaf tissue nuclei. In vivo treatments resulted in only one mixoploid plant. In vitro treatments resulted in one mixoploid and one tetraploid plant. The tetraploid plant exhibited shorter internodes and shorter leaves than its diploid counterpart and is under evaluation for suitability as a new variety or for use in hybridizing efforts.