Plantlet regeneration and bulbil formation in vitro from leaf and stem explants of Curculigo orchioides, an endangered medicinal plant

Abstract

A method has been developed for rapid multiplication of Curculigo orchioides (Hypoxidaceae) through direct organogenesis and bulbil formation in vitro. Leaf and underground stem explants produced maximum number of shoots (four and 10 per explant, respectively) on B5 medium supplemented with 4.4 μM BAP. Higher concentrations of BAP (≥22 μM) in the medium completely inhibited the growth and shoot proliferation from the leaf explants. Stem-disc-derived callus produced numerous bulbils on the medium containing BAP (8.8–35.2 μM) and sucrose (0.12–0.23 M). Maximum number of bulbils (10 per explant, 0.19 g fresh weight per bulbil) were recorded on the medium supplemented with 35.2 μM BAP and 0.18 M sucrose. Isolated bulbils increased in size (maximum growth index 36.4) and produced secondary bulbils on transfer to medium of the same composition. A maximum number of secondary bulbils (six per bulbil) were produced on the medium containing 35.2 μM BAP and 0.23 M sucrose. Growth of in vitro produced bulbils into plantlets and rhizogenesis from isolated shoots was achieved on the medium devoid of plant growth regulators. Small plantlets developed in vitro were successfully (90% survival) transferred to the soil. Plantlets sprouted in the next season (June 1997) after over-wintering.