Polyploidization of Japanese quince plants

In this paper, studies on in vitro polyploidization of Japanese quince (Chaenomeles japonica) are reported. Tetraploid and mixoploid plants were obtained both when microshoots and cotyledons were treated with colchicine or oryzalin. In general, morphogenesis seemed to be more dependent on the concentration than on time and duration of treatment. High colchicine concentrations were toxic for Japanese quince microshoots, but genotype differences were also observed. Although high oryzalin concentrations inhibited growth, intermediate and low concentrations were very efficient for induction of polyploids without severe negative effects on shoot growth. The optimal concentration for polyploidization of microshoots was 0.6–0.9% for colchicine and 30–40 μM for oryzalin. The optimal concentration for polyploidization of excised cotyledons was 0.3–0.6% for colchicine, and 20–40 μM for oryzalin. For efficient polyploidization, cotyledons should not be treated with colchicine until four days after excision, whereas oryzalin should be applied immediately