Factors influencing in vitro plant regeneration of Liquorice (Glycyrrhiza glabra L.)

An efficient and reproducible in vitro protocol for largescale multiplication of Liquorice (Glycyrrhiza glabra L.)has been described. Multiple shoots formation was significantly influenced by growth regulators, photoperiod,explant position, season of explant collection and culture passage. Nodal explants were collected atmonthly intervals to initiate in vitro cultures. The highest bud-break (86.6%) with the longest shoot length(8.0 cm) and maximum number of shoots (3.0) was obtained when middle order nodes (3rd to 5th nodefrom apex) collected between May to August were inoculated on MS medium supplemented with 6-Benzylaminopurine (2.0 mg/l) + α-naphthalene acetic acid (0.5 mg/l) under photoperiod of 16/8 h (light/dark cycle). The induction of multiple shoots was also affected by photoperiod and subculture cycle. Multiple shoots formation increased from the first (2.2) to the fourth subculture (6.6). The in vitro regenerated shoots were induced on half strength MS medium enriched with 1.0 mg/l IAA resulting early rooting and maximum root growth. Plantlets were hardened and successfully established in the soil. Concentration of chlorophyll, total sugars, reducing sugars and proteins were estimated in leaf tissues from both in vivo and in vitro raised plants. Chlorophyll content was higher in in vivo plants, whereas other three components were higher in micropropagated plants. The present optimized micropropagation protocol offers the possibility ofgermplasm conservation and mass cultivation of this important medicinal plant.