Determination by flow cytometry of the chromosome doubling capacity of colchicine and oryzalin in gynogenetic haploids of gerbera.

In vitro plants of the gynogenetic haploid line 86122/560 of gerbera were treated with colchicine or oryzalin dissolved in dimethylsulfoxide, to compare the antimitotic efficiency of these substances. The ploidy level was evaluated by flow cytometry two months after the treatment. Decrement of the multiplication rate was taken into account for the evaluation of the toxic effect of the antimitotic substances. Controls both with and without dimethylsulfoxide maintained the haploid status. At comparable doses, oryzalin proved to be as efficient as colchicine, but slightly less phytotoxic. Longer oryzalin treatments could probably induce the diploidization of a larger number of cells and reduce the problem of chimaeric plants.