Abstract
An investigation was conducted to study the effects of explant sources, plant growth regulators, carbohydrates and light conditions on indirect cormlet regeneration and the induction of embryogenic callus of freesia (Freesia × hybrida Bailey ‘Argenta’). Sections of two different types of explants, corms and pupae (cold storage-produced corms), were placed on Murashige and Skoog (MS) media containing different concentrations of plant growth regulators. The results showed that the highest percentage of callus induction (100%), the highest callus growth (15 mm diameter) and the best type of calli were achieved for pupa explants grown on the medium that contained 4 mg L−1 1-naphthaleneacetic acid (NAA) and 2 mg L−1 6-benzylaminopurine (BAP) in the dark. Increasing BAP up to 3 to 4.5 mg L−1 resulted in the maximum number of regenerated cormlets from 1 cm2 calli (2 cormlets) under light conditions. Overall, the best rooting of regenerated cormlets was achieved on MS media supplemented with 1 mg L−1 indole-3-butyric acid (IBA). In the next stage, high quality calli were subcultured on MS media containing sorbitol, sucrose, maltose and mannitol (0, 5, 10 and 15 g L−1). The results indicated that 15 g L−1 maltose was able to induce the highest percentage of embryogenic callus, with an average of 88.9% on media containing 2 mg L−1 BAP and 1 mg L−1 NAA.