Pupae are excellent explants with low microbial contamination and high regeneration frequency for micropropagation of Freesia ×hybrida Bailey 'Argenta'

Abstract

Two separate factorial experiments were conducted to study the effects of explant sources, plant growth regulators, sucrose concentrations, and light conditions on in vitro cormlet formation of freesia (Freesia ×hybrida Bailey 'Argenta'). Interestingly, it was observed that the pupae had lower contamination levels compared to mother corms. Using 40% sodium hypochlorite solution for 40 min, contamination levels of pupae and mother corms reduced to 19.80 and 46.40%, respectively. Moreover, pupae showed the highest regeneration frequency. In the first experiment, 6.67 cormlets were directly produced per pupa (cold storage-produced corm) on Murashige and Skoog (MS) medium supplemented with 6 mg L-1 1-naphthaleneacetic acid (NAA), 1 mg L-1 6-benzylaminopurine (BA), and 60 g L-1 sucrose, when cultures were stored in the dark. In the second experiment, on average, 5.67 shoots were proliferated per pupa explant in the presence of 4 mg L-1 BA and 2 mg L-1 Kinetin (Kin). Subculturing these shoots on MS medium containing 3 mg L-1 BA and 0.5 mg L-1 NAA led to production of 3.67 cormlets per shoot. Finally, in vitro derived cormlets showed the highest percentage of rooting (77.80%), root number (8.33), and root length (2.13 cm) on MS medium containing 1 mg L-1 indole-3-butyric acid (IBA).