Effectiveness of colchicine and oryzalin at inducing polyploidy in Watsonia lepida N.E. Brown

Genetic modification and manipulation offers the possibility of introducing novel traits into existing plants, thereby increasing marketability. Polyploid induction has in the past produced plants that are more compact and have larger flowers, leaves, and fruit, making them more desirable to consumers. The effect of pulse treatments (0, 24, 48, and 72 h) of colchicine (25, 50, 125, and 250 μM) or oryzalin (30, 60, 90, and 120 μM) on in vitro-grown Watsonia lepida N.E. Brown shoots was investigated. Explant survival was higher and more consistent with oryzalin treatment compared with treatment with colchicine. More mixoploids than tetraploids were produced with both compounds. The optimum treatment for producing tetraploids was 120 μM oryzalin for 24 h. Of the 30% explants that survived this treatment, 33% were found to be stable tetraploids.