In vitro regeneration in Dierama erectum Hilliard

The genus Dierama comprises plants with a potential to be developed as ornamentals. D. erectum seeds were decontaminated and germinated on 1/10th strength Murashige and Skoog (Physiol Plant 15:473-497, 1962) (MS) media without plant growth regulators or sucrose. In an experiment investigating the effects of 6-benzyladenine (BA), meta-Topolin (mT), kinetin (KIN) and zeatin (Z) with or without alpha-naphthaleneacetic acid (NAA), the highest shoot number per hypocotyl (4.20 +/- A 0.51) was obtained from MS medium supplemented with 1.0 mu M Z after 8 weeks. This was followed by a combination of 2.0 mu M KIN and 2.0 mu M NAA with 3.67 +/- A 0.81 shoots per explant. BA treatments produced 3.20 +/- A 0.22 shoots per hypocotyl explant when 2.0 mu M was combined with 1.0 mu M NAA, while mT gave 3.09 +/- A 0.99 shoots per explant when 2.0 mu M mT was combined with 2.0 mu M NAA. Adventitious shoot regeneration was optimised when shoots were grown under a 16-h photoperiod at 100 mu mol m(-2) s(-1) on MS medium supplemented with 1.0 mu M BA. This resulted in an average of 12.73 +/- A 1.03 shoots per hypocotyl explant. Various concentrations of ancymidol, activated charcoal and sucrose did not promote in vitro corm formation of this species. Plants rooted successfully after 8 weeks on MS medium supplemented with 1.0 mu M indole-3-butyric acid (IBA) and had an average root number of 2.73 +/- A 0.40. After 2 months of acclimatisation, plants had formed corms. The largest corms (of diameter 0.45 +/- A 0.03 cm) were produced in plants pre-treated with 0.5 mu M IBA. The highest plant survival percentage of 73% was also associated with this treatment.