IN VITRO PROPAGATION OF Curculigo orchioides Gaertn., COLLECTED FROM HOA BINH WARD, PHU THO PROVINCE

Abstract

Curculigo orchioides Gaertn. is a valuable medicinal species, widely used in traditional medicine. Currently, wild populations of C. orchioides are declining and they are classified as endangered species (EN) in the 2024 Vietnam Red Data Book. Therefore, in vitro propagation represents a crucial approach for conserving and sustainably developing this species. Rhizome cross-section (RCS) and in vitro leaf segments (ILS) were used as explants for propagation on basal Murashige and Skoog (1962) (MS) medium supplemented with 3% sucrose, 0.1% activated charcoal, 0.7% agar. Plant growth regulators, including 6-benzylaminopurine (BAP) and thidiazuron (TDZ) at 0.5 - 2 mg/L combined with indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA) at 0.5 mg/L, were applied to evaluate callus induction, shoot regeneration and plantlet formation. Results indicated that rhizome explants were sterilized with 0.1% HgCl₂ for 16 minutes, yielded 83.33% clean cultures after 4 weeks. MS medium supplemented with 1.5 mg/L TDZ and 0.5 mg/L IBA was optimal for direct shoot regeneration from RCS and ILS, achieving 98.9 - 100% regeneration, 5.72 - 7.85 shoots per explant and shoot lengths of 4.85 - 5.39 cm. Callus induction was most effective on MS medium containing 1.5 - 2 mg/L IBA and 1 mg/L TDZ producing 100% callus formation, 92.22 - 100% shoot regeneration and 3.67 - 4.63 shoots per explant after 10 weeks. Shoot regeneration from callus on MS medium 1.0 mg/l TDZ + 0.5 mg/l NAA supplemented with 3% sucrose, 0.1% activated carbon, 0.7% agar reached 97.78% regeneration, 9.97 shoots per culture and 4.41 cm/shoot). Complete plantlets were rooted on MS medium with 1.5 mg/L IBA, showing 97.78% rooting, 7.13 roots per shoot, 5.33 cm root length, thick, white and highly branched roots. Acclimatization on a substrate of B-horizon soil, rice husk and coconut coir (2: 1: 1) resulted in 83.33% survival, with an average height increase of 2.04 cm after one month.