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 <em>in vitro</em> cormlet formation of freesia (<em>Freesia</em> ×<em>hybrida </em>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, <em>in vitro</em> 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^-1indole-3-butyric acid (IBA).