Large-scale in vitro propagation of Impatiens repens Moon., a critically endangered medicinal plant in Sri Lanka

Abstract

SummaryImpatiens repens Moon. (Ceylon Balsam: Family Balsaminaceae) is an endemic, critically endangered, medicinal plant in Sri Lanka. Habitat destruction and over-exploitation have resulted in the virtual extinction of this species. To grow this plant sustainably, a micropropagation protocol was developed using nodal explants for rapid, large-scale propagation. Nodal segments were established on Murashige and Skoog (MS) medium supplemented with different combinations of 6-benzylaminopurine (BAP) and Kinetin for shoot induction. Shoots were established on MS medium supplemented with different combinations of BAP and indole-3-acetic acid (IAA) for shoot multiplication. Micro-shoots were established on full-strength or half-strength MS medium supplemented with different concentrations of α-naphthalene-acetic acid (NAA) for root induction. MS medium supplemented with 2.0 mg l–1 BAP and 1.0 mg l–1 Kinetin gave the highest mean number of shoots per nodal explant (4.7), the highest mean shoot length (3.2 cm), and the highest frequency of shoot regeneration (100%). Addition of a combination of BAP and IAA significantly influenced shoot multiplication. The highest mean number of shoots per shoot explant (18.8) was observed on MS basal medium supplemented with 2.0 mg l–1 BAP and 0.1 mg l–1 IAA. The highest mean number of roots per shoot, mean root length, and frequency of rooting were observed on half-strength MS medium supplemented with 1.0 mg l–1 NAA. Plantlets were acclimatised, with a 96% survival rate, on a 3:1 (v/v) mix of sand: compost (leaf mould).